| Song Title | Artist | Topic |
| O Caroline | Matching Mole | regrets |
| O Circo Chegou | Jorge Ben | the circus |
| O Death | Ralph Stanley | death |
| O Galho da Roseira | Airto Moreira | roses |
| O Majhi Re | Shaan & Saurav Moni | arresting opening lines |
| O Mar | Dorival Caymmi | the coast |
| O Mary Don’t You Weep | Bruce Springsteen & the Seeger Sessions Band | miracles |
| O mio babbino caro (from Gianni Shicchi) | Giacomo Puccini (sung by Amira Willighagen) | melancholy songs |
| O Pencil Sharp | Drive Like Jehu | without a chorus |
| O Sole Mio | Blind John Davis | classical songs |
| O Superman (For Massenet) | Laurie Anderson | spoken word |
| O Superman (For Massenet) | Laurie Anderson | aliens |
| O Thou That Tellest Good Tidings to Zion | Stevie Wonder & Take 6 | a cappella |
| Oatmeal | Sudan Archives | waking up |
| Obama Nation | Lowkey | US presidents |
| Obirin African (Woman of Africa) | Art Blakey & the Afro-Drum Ensemble | Africa |
| Obscurity Knocks | The Trash Can Sinatras | fractions & portions |
| Obsesión | Aventura ft Judy Santos | songs in Spanish |
| Obvious | The Elephants | the obvious |
| Occasional Rain | Terry Callier | water |
| Ocean | The Velvet Underground | notable outros or codas |
| Ocean Eyes | Billie Eilish | eyes |
| Ocean in the Night | Elephant Gym | unusual time signatures |
| The Ocean Is Teacher | Tom Furse | teachers |
| Ocean Rain | Echo & the Bunnymen | mixtape closers |
| Ocean Size | Jane’s Addiction | wide open spaces |
| Ocean Spray | Manic Street Preachers | nursing & healthcare |
| October Night | Witch | September & October |
| October Song | Amy Winehouse | September & October |
| Octopus’s Garden | The Beatles | underwater |
| Odd Jobs | Captain Beefheart & His Magic Band | decor |
| Odds & Ends | ryo/supercell ft Hatsune Miku | audible breaths |
| Odds Are | Barenaked Ladies | survival |
| Ode to Billie Joe | Bobbie Gentry | storytelling songs |
| Ode to Boy | Yazoo | beauty |
| Ode to Jackie Leven | Tyla J. Pallas | biography & autobiography |
| Ode to Joy | Ludwig van Beethoven | hope & resilience |
| Ode to My Family | The Cranberries | family |
| Ode to the Bouncer | Studio Killers | borders, barriers, walls & fences |
| Odessa | Caribou | divorce |
| Odyssey | Symphony X | songs that express excess |
| Off the Wall | Michael Jackson | triggering dancing |
| Offerings | Gil Scott-Heron & Brian Jackson | staying |
| Official Suburbian Superman | Suzi Quatro | spring cleaning & household chores |
| Offshore Banking Business | The Members | taxation |
| O.F.N.I. (Objeto Flamenco No Identificado) | UHF (Ultra High Flamenco) | supergroups |
| Ogdens’ Nut Gone Flake | Small Faces | instrumentals |
| Oh Better Far to Live and Die | Gilbert and Sullivan | kings |
| Oh Bondage Up Yours! | X-Ray Spex | great opening lines |
| Oh Carolina | Folkes Brothers | lesser known originals |
| Oh Death | Charley Patton & Bertha Lee | COVID-19 lockdown |
| Oh England My Lionheart | Kate Bush | England |
| Oh Good Ale | The Copper Family | beer |
| Oh Happy Day | Edwin Hawkins Singers | call and response |
| Oh Happy Day | Edwin Hawkins Singers | spiritual songs |
| Oh I Swear | Richard Thompson | can’t live with or without you |
| Oh Larsen B | British Sea Power | cold |
| Oh Lord, Don’t Let Them Drop That Atomic Bomb on Me | Charles Mingus | nuclear war |
| Oh Lord, Why Lord | Los Pop Tops | classical songs |
| Oh Mary | Neil Diamond | deep voices |
| Oh My God | Michael Franti & Spearhead | conspiracy theories & paranoia |
| Oh My God | Katzenjammer | genre defying |
| Oh My Gosh | Basement Jaxx | flirting |
| (Oh No! I Must Have Said) Yes | Van der Graaf Generator | misunderstanding |
| Oh No Not My Baby | Maxine Brown | gossip |
| Oh No Not My Baby | Maxine Brown | disbelief |
| Oh, Pretty Woman | Roy Orbison | change of mind |
| Oh Sweet Nuthin’ | The Velvet Underground | nothing |
| Oh, the Divorces! | Tracey Thorn | divorce |
| Oh What a Beautiful Mornin’ | Gordon MacRae | bright and beautiful |
| Oh What a World | Rufus Wainwright | great arrangements |
| Oh Yeah | Roxy Music | radio |
| Oh Yeah | Yello | audible breaths |
| Oh! You Pretty Things | David Bowie | oddballs, outcasts & outsiders |
| Ohio | Crosby, Stills, Nash & Young | protest |
| Ohio/Machine Gun | The Isley Brothers | higher education |
| Ohio River Boat Song | Bonnie “Prince” Billy | rivers |
| Ohio Town Saved from Killer Bees by Hungry Vampire Bats | Jad Fair & Yo La Tengo | newspapers |
| Ohm Sweet Ohm | Kraftwerk | resistance |
| Oi Can’t Git a Noice Loaf a Bread | The Singing Postman | bread & baking |
| The Oil Song | Steve Forbert | scandal |
| Oiseaux exotiques | Olivier Messiaen (performed by Daniel Kirk-Foster) | birdsong |
| Okie from Muskogee | Merle Haggard | pride |
| Okinawa Song – Chin Nuku Juushii | Ryuichi Sakamoto | Asian cities |
| Okra | Olu Dara | markets & fairs |
| Ol’ Man River | Screamin’ Jay Hawkins | rivers |
| Old | Dexys Midnight Runners | old age |
| Old 45s | Chromeo | hearing, choosing & playing records |
| Old Age Killed My Teenage Bride | Half Man Half Biscuit | ages |
| The Old Ark’s A’Moving | A. A. Gray & Seven Foot Dilly | children’s songs |
| Old Blue | Odetta & Larry | pets |
| Old Codger | The Stranglers & George Melly | unlikely collaborations |
| Old Enough | The Raconteurs | violin |
| Old Fart at Play | Captain Beefheart & His Magic Band | masks |
| Old Gopher | Edgar Broughton Band | American west |
| Old King | Neil Young | pets |
| The Old Main Drag | The Pogues | finish where they begin |
| Old Man | Love | gifts & giving |
| Old Man | Neil Young | old age |
| The Old Man’s Back Again (Dedicated to the Neo-Stalinist Regime) | Scott Walker | politicians |
| Old McDonald Had a Farm | Ella Fitzgerald | farming |
| Old Molly Metcalfe | Jake Thackray | tradition |
| Old, New Bicycle | Helvetia | bicycles |
| Old Red Eyes Is Back | The Beautiful South | eyes & sight |
| Old Rugged Cross | Rahsaan Roland Kirk | crosses |
| Old School | Danger Doom ft Talib Kwei | television |
| Old September Blues | My Morning Jacket | September |
| Old Tart’s Song | Poison Girls | wanting to be someone else |
| Old Wild Men | 10cc | old age |
| Olde Tyme Mem’ry | Mischief Brew | authenticity & fakery |
| Oliver’s Army | Elvis Costello & the Attractions | Britain |
| Olympia | Hole | US cities & states |
| Ombra mai fu | George Frideric Handel (sung by Andreas Scholl) | falsetto |
| OMG | The Streets ft Laura Vane | acronyms |
| Ominous Cloud | Broadcast | clouds |
| On a Clear Day You Can See Forever | The Peddlers | wide open spaces |
| On a Good Day | Joanna Newsom | harp, lyre & zither |
| On a Monday | Lead Belly | judges & trials |
| On a Poet’s Lips I Slept (from Nocturne) | Benjamin Britten | inspired by poetry |
| On a Wedding Anniversary | John Cale | anniversaries |
| On Broadway | The Drifters | roads & streets |
| On Days Like These | Matt Monro | Italy |
| On est chez nous | Zebda | France |
| On Hearing the First Cuckoo of Spring | Frederick Delius | interlopers |
| On Her Majesty’s Secret Service | John Barry | trombone |
| On Morecambe Bay | Christy Moore | tides |
| On My Radio | The Selecter | radio |
| On Some Faraway Beach | Brian Eno | wide open spaces |
| On Sunday Afternoon | The Harptones | afternoon |
| On the Border | Al Stewart | borders, barriers, walls & fences |
| On the Bus Mall | The Decemberists | buses |
| On the Edge of a Cliff | The Streets | chance & coincidence |
| On the Horizon | Ben E. King | horizons |
| On the Improve | John Williamson | recovery |
| On the Nature of Daylight | Max Richter | lower the heartrate |
| On the Nickel | Tom Waits | crisis |
| On the Radio | Regina Spektor | radio |
| On the Radio | Donna Summer | songs with sudden changes |
| On the Run | The Jompson Brothers | being scared |
| On the Run | Pink Floyd | vibrato, tremolo & oscillations |
| On the Shelf | Jake Thackray | being single |
| On the Sunny Side of the Street | Louis Armstrong | hope & resilience |
| On Tooting Broadway Station | Kitchens of Distinction | forgiveness |
| Once I Dreamt a Tree Upside Down | Jan Garbarek Group | inversions |
| Once I Was | Tim Buckley | legacy |
| Once in a Lifetime | Angélique Kidjo | underwater |
| Once in a Lifetime | Talking Heads | mistaken identity |
| Once More with Feeling | Traffic Experiment | stuck or trapped |
| Once There Was a Wintertime | Cornershop ft Bubbley Kaur | winter |
| Once Upon a Dream | Lana Del Rey | fairytales |
| One | Johnny Cash | numbered 1 to 10 |
| One | Metallica | songs that build |
| One Armed Scissor | At the Drive-In | aliens |
| One Black Rat | Big Mama Thornton | rodents |
| One Brief Moment | Natacha Atlas | brevity |
| One Chord Wonders | The Adverts | the number one |
| One Day | Fatoumata Diawara | treasure |
| One Day at a Time | Joe Walsh | resilience |
| One Day Like This | Elbow | euphoria |
| One Evening | Feist | evening |
| One Fine Day | The Chiffons | optimistic songs |
| One Flew Over the Cuckoo’s Nest (Opening Theme) | Jack Nitzsche | odd noises & instruments |
| One for My Baby (And One More for the Road) | Frank Sinatra | pubs & bars |
| One Horse Town | Blackberry Smoke | roots |
| The One I Love | R.E.M. | songs that aren’t what they seem |
| One in Ten | UB40 | ‘I am’ songs |
| One Is the Magic Number | Jill Scott | being single |
| One Last Breath | Creed | redemption |
| One Love / People Get Ready | Bob Marley & the Wailers | unity |
| One Man Guy | Loudon Wainwright III | volume |
| One Man Guy | Rufus Wainwright | being alone |
| One May Morning Early | Bellowhead | nightingales & thrushes |
| One Million Coasters | NOFX | plastic |
| One Mint Julep | The Clovers | the number one |
| The One Moment | OK Go | impressive videos |
| One Moment More | Mindy Smith | the number one |
| One More | The Weaves | the number one |
| One More Addiction | Natalie Imbruglia | addiction |
| One More Breath | Richard Thompson | breathing |
| One More Cup of Coffee | Bob Dylan | coffee |
| One More Mile to Go | Otis Spann | the number one |
| One More Robot / Sympathy 3000-21 | The Flaming Lips | artificial intelligence |
| One More Time | Daft Punk ft Romanthony | repetition |
| One More Try | George Michael | education |
| One Nation Under a Groove | Funkadelic | unity |
| One Night in Bangkok | Murray Head | specific or obscure places |
| One Night Stand | The Aloof | one night stands |
| One Night Stand | The Partridge Family | strangers |
| One Note Samba | The New Stan Getz Quartet with Astrud Gilberto | meta-songs |
| One Note Samba | Mann – Herbie with João Gilberto and Antônio Carlos Jobim | austerity |
| One of Our Submarines | Thomas Dolby | underwater |
| One of These Things First | Nick Drake | failure |
| One of Us Must Know (Sooner or Later) | Mick Hucknall / Bob Dylan | misunderstanding |
| The One on the Right Is on the Left | Johnny Cash | inversions |
| One People, One Struggle | Anti-Flag | the number one |
| One Piece at a Time | Johnny Cash | smuggling & stealing |
| One Scotch, One Bourbon, One Beer | Amos Milburn | numbers |
| One Second to Midnight | Icons of Filth | the number one |
| One Size Never Fits | Matt Andersen | stereotypes |
| One Step Beyond | Madness | echoes |
| One Step Forward | Max Romeo & the Upsetters | regressing & reversing |
| One Thousand Cherry Trees | Hatsune Miku | substitutions |
| One Too Many Mornings | Joan Baez | misunderstanding |
| One Way | Levellers | sinners |
| One Way Glass | Manfred Mann Chapter Three | glass |
| One Way or Another | Blondie | confidence |
| One Way Out | Sonny Boy Williamson II | windows |
| One Week | Barenaked Ladies | extraordinary vocals |
| One Week | Say Sue Me | brevity |
| Oneness with the Forest | Bobby Brown | forests & woodlands |
| One’s on the Way | Loretta Lynn | babies & childbirth |
| The Onion Song | Marvin Gaye & Tammi Terrell | vegetables |
| Online | Brad Paisley | substitutions |
| Only | Anthrax | one word titles |
| Only a Dream | Mary Chapin Carpenter | leaving or being left behind |
| Only a Northern Song | The Beatles | non sequiturs |
| Only a Pawn in Their Game | Bob Dylan | shooting |
| The Only Living Boy in New Cross | Carter the Unstoppable Sex Machine | London |
| Only Love Can Break Your Heart | Saint Etienne | covers better than the original |
| Only Remembered | Coope Boyes and Simpson | a cappella |
| Only Shallow | My Bloody Valentine | adult lullabies |
| Only So Much Oil in the Ground | Tower of Power | wells |
| Only the Stones Remain | The Soft Boys | impermanence |
| The Only Way Is Up | Yazz and the Plastic Population | recovery |
| Only When I’m Drunk | Tha Alkaholiks | drinking |
| Only Women Bleed | Alice Cooper | feminism |
| Onomatopeia | Todd Rundgren | odd noises & instruments |
| O-o-h Child | The Five Stairsteps | consolation |
| Ooh Las Vegas | Emmylou Harris | gambling |
| Oops!… I Did it Again | Britney Spears | guilt & apology |
| Oops (Oh My!) | Tweet ft Missy Elliott | sexy songs |
| Open All Night | Bruce Springsteen | songs that build |
| Open Country Joy | Mahavishnu Orchestra | violin |
| An Open Letter to NYC | Beastie Boys | peace |
| Open My Eyes | Nazz | songs to start the morning |
| Open the Door Homer | Bob Dylan & the Band | doors |
| Open Up | Leftfield | California |
| Open Up Your Door | Richard Hawley | doors |
| Open Up Your Heart (And Let the Sun Shine In) | Pebbles and Bamm Bamm | bright and beautiful |
| Open Your Eyes | Angélique Kidjo | eyes |
| Ophelia | Natalie Merchant | feminism |
| Opium | Dead Can Dance | recreational drugs |
| Opportunities (Let’s Make Lots of Money) | Pet Shop Boys | nerds & geeks |
| Opportunity | Bobby McFerrin | covers by the opposite sex |
| Optimistic | Sounds of Blackness | positive songs |
| Opus in Beige | Stan Kenton | colours |
| Opus Pocus | Jaco Pastorius | hammer & mallet instruments |
| Orange | Passepied | orange |
| Orange | Psychostick | fruit |
| Orange Blossom Special | Charlie McCoy | harmonica |
| Orange Claw Hammer | Captain Beefheart & the Magic Band | shaggy dog stories & tall tales |
| Orange Colored Sky | Nat King Cole | orange |
| Orange Crush | R.E.M. | spine & neck |
| Orange Moon | Erykah Badu | colours |
| Orange Peel | Reuben Wilson | orange |
| Orange Rolls, Angel’s Spit | Sonic Youth | bread & baking |
| Oranges and Lemons | Jools Holland & Suggs | fruit |
| Orca Song | Tulku | cetaceans |
| The Orchids | Psychic TV | tattoos & piercings |
| Ordinary Angels | Frente! | normal & abnormal |
| Ordinary Average Guy | Joe Walsh | normal & abnormal |
| Ordinary Joe | Terry Callier | mixtape closers |
| Organ Eternal | These New Puritans | eternity |
| Original Stuntmaster | Aim | safety & danger |
| Original Suffer-Head | Fela Kuti | reckless consumption |
| Oro Santo | Javier Limón with Concha Buika | favourite live versions |
| Ory’s Creole Trombone | Ory’s Sunshine Orchestra | trombone |
| The Osmonds | Denim | Birmingham & the Black Country |
| Oswald Defence Lawyer | The Fall | judges & trials |
| The Other Man | Sloan | substitutions |
| The Other Side | Public Service Broadcasting | musically adventurous |
| The Other Window | Wire | strange & surreal |
| Otis | The Durutti Column | genre defying |
| Otomo | Tarwater | itching & scratching |
| Otona no Ookami | KOKIA | wolves |
| Oualahila Ar Tesninam | Tinariwen | call and response |
| Oumniya | Souad Massi | prayer |
| Our Country | Illy | Australia |
| Our House | Madness | home |
| Our Lips Are Sealed | The Go-Go’s | silence |
| Our Lives Are Shaped by What We Love | Odyssey | meaning of life |
| Our Mutual Friend | The Divine Comedy | tragedy & comedy |
| Our Prayer | The Beach Boys | short songs |
| Our Retired Explorer (Dines with Michel Foucault in Paris, 1961) | The Weakerthans | specific or obscure places |
| Our Skulls | Imaad Wasif | bones |
| Our Spring Will Come | John Cage | piano songs |
| Our Sunshine | Paul Kelly | outlaws & rebels |
| Our Town | Iris DeMent | leaving or being left behind |
| Our Way to Fall | Yo La Tengo | memory |
| Our Wedding | Crass | songs that aren’t what they seem |
| ’Ouses, ‘Ouses, ‘Ouses | The Imagined Village | urban environment |
| Out in the Country | Paul Williams | simple pleasures |
| Out in the Fields | Gary Moore & Philip Lynott | flags |
| Out in the Street | Bruce Springsteen | the weekend |
| Out of a Serpent’s Egg | Dead Can Dance | eggs |
| Out of My Book | Van der Graaf Generator | flutes, pipes & whistles |
| Out of Time | The Rolling Stones | schadenfreude |
| Out of Time Man | Mano Negra | punctuality |
| Out on the Floor | Dobie Gray | mood-changing music |
| Out on the Weekend | Neil Young | the weekend |
| Outdoor Miner | Wire | insects |
| The Outdoor Type | The Lemonheads | funny songs |
| Outer Space | John Grant | space |
| Outro (I’m a Fool to Want You) | M. Ward | fools |
| Outside the Trains Don’t Run on Time | Gang of Four | obsession |
| Outside This Bar | American Music Club | pubs & bars |
| Outsider | Ramones | oddballs, outcasts & outsiders |
| Outubro | Milton Nascimento | months of the year |
| Oval Room | Blaze Foley | US presidents |
| Over and Over | Hot Chip | repetition |
| Over at the Frankenstein Place | Barry Bostwick, Susan Sarandon & Richard O’Brien | lighthouses & guiding lights |
| Over the Border | Saint Etienne | made you fall in love with music |
| Over the Edge of the World | Virginia Astley | horizons |
| Over the Hills and Far Away | John Tams | kings |
| Over the Hillside | The Blue Nile | horizons |
| Over the Rainbow | Jeff Beck | covers by the opposite sex |
| Over the Rainbow | Judy Garland | recorded for movies |
| Over the Wall | Echo & the Bunnymen | obstacles |
| Overdose of Joy | Eugene Record | euphoria |
| Overjoyed | Esperanza Spalding | double bass |
| Overnight | Maggie Holland | itinerants & migration |
| Overnight Sensation | Raspberries | false endings |
| The Owl | Slapp Happy & Henry Cow | owls |
| Owl Eyes | Devendra Banhart | owls |
| The Owl of Love | Clogs ft Shara Worden | owls |
| An Owl Song | Canned Heat | owls |
| Owls | The Handsome Family | decor |
| Oxford Comma | Vampire Weekend | wealth |
| Oxford Street | Everything but the Girl | coming of age |
| Oxford Town | Richie Havens | justice |
| Oxygen | Feeder | breathing |
| Oxygen | Willy Mason | protest |
| Oxygène | Jean-Michel Jarre | gases |