| Orono Cemetery Company | Bowmanville | — |
| Orono Crown Lands Trust | Orono | $17K |
| Orono Kirby Pastoral Charge | Orono | $138K |
| Orphanage & Destitute Families Concern | Etobicoke | $17K |
| Orpheum Theatre Foundation | Vancouver | $1 |
| Orpheus Musical Theatre Society | Ottawa | $1M |
| ORT Canada | North York | $2M |
| Orthodox Brotherhood of ST Euphrosynia | Stouffville | — |
| Orthodox Church of the Assumption of the Holy Virgin | Lethbridge | $83K |
| Orthodox Community of Saint Paul | Burlington | $2,500 |
| Orthodox Missionary Church Saint Vasiliye of Ostrog Canada | Richmond Hill | $88K |
| Orthodox Rabbinical Council of British Columbia | Vancouver | $1.8M |
| Orthodox V Charitable Association | Lamont | $30K |
| Orton Community Association | East Garafraxa | $73K |
| Ortonville Baptist Church | Grand Falls | $49K |
| Orville and Alvera Woolacott Foundation | Toronto | $38K |
| Osage Church Historical Society | Indian Head | $6,863 |
| Osaid (ontario Students Against Impaired Driving) Inc. | Toronto | $42K |
| Osborn Foundation of Canada | Toronto | $19K |
| Osborne Cemetery Association | Lockeport | $11K |
| Osborne House Inc. | Winnipeg | — |
| Osborne Village Church INC. | Winnipeg | $171K |
| Osborne Village Resource Centre Manitoba Incorporated | Winnipeg | $449K |
| OSCA Foundation | Mississauga | — |
| OSEG Foundation | Ottawa | $1.5M |
| Oseredok Ukrainian Cultural and Educational Centre Inc. | Winnipeg | $689K |
| Osgoode Baptist & Vernon United Church | Vernon | $126K |
| Osgoode Care Centre | Metcalfe | $11.8M |
| Osgoode CO-Operative Nursery School Inc. | Osgoode | — |
| Osgoode-Kars United Church | Osgoode | $81K |
| Osgoode Presbyterian Church | Metcalfe | $73K |
| Osgoode Township Rural Museum | Vernon | $263K |
| Osgoode Youth Association | Osgoode | $307K |
| Oshawa Civic Band Inc. | Whitby | $9,415 |
| Oshawa Clarington Community Living Foundation | Oshawa | — |
| Oshawa & District Ostomy Association | Simcoe | $1,575 |
| Oshawa-Durham Rape Crisis Centre | Oshawa | $918K |
| Oshawa Generals Foundation | Oshawa | $45K |
| Oshawa Group Limited Employees' Charitable Trust | Stellarton | $90K |
| Oshawa Parkwood Rotary Club Charitable Foundation | Oshawa | $51K |
| Oshawa Public Library Board | Oshawa | $10.7M |
| Oshawa Senior Community Centres | Oshawa | $5.2M |
| Oshawa - Whitby Kiwanis Music & Theatre Festival | Whitby | — |
| Oshki-Giizhig Inc. | Winnipeg | $6.5M |
| Oshki-Pimache-O-Win: The Wenjack Education Institute | Thunder Bay | $9.9M |
| Oskâpêwis Gladue Services | Calgary | $0 |
| Osler Community Church Inc. | Osler | $193K |
| Osler Community Pioneers Inc | Osler | $19K |
| Osler Mennonite Church Inc. | Osler | $228K |
| Osler Mission Chapel Inc. | Osler | $697K |
| Osmow's Hope Fund | Mississauga | $107K |
| OSNS Legacy Foundation | Penticton | $176K |
| Osoyoos and District Arts Council | Osoyoos | $87K |
| Osoyoos Baptist Church | Osoyoos | $171K |
| Osoyoos Child Care Centre Society | Osoyoos | $37K |
| Osoyoos Christian Centre | Osoyoos | $110K |
| Osoyoos Desert Society | Osoyoos | $266K |
| Osoyoos Lake Water Quality Society | Osoyoos | $14K |
| Osoyoos Museum Society | Osoyoos | $209K |
| Osoyoos Secondary Scholarship Foundation | Osoyoos | $21K |
| Osoyoos Secondary School Transportation Society | Osoyoos | — |
| Osoyoos Seniors Centre Association | Osoyoos | $90K |
| Osoyoos United Church | Osoyoos | $101K |
| Osprey Arts Centre Association | Shelburne | $198K |
| Osprey Community Foundation | Nelson | $1.7M |
| Osprey Museum | Feversham | $104K |
| Ossington Avenue Baptist Church | Toronto | $183K |
| Ossington Pentecostal Church | Toronto | $407K |
| Osstf Humanity Fund | Toronto | $42 |
| Ostenfeld Lutheran Church | Anola | $15K |
| Osteoporosis Canada / Osteoporose Canada | North York | $6.4M |
| Ostéothèque de Montréal Inc. | Montreal | $10K |
| Ostermann Oel Foundation | Calgary | $13K |
| Ostomy Canada Society Inc. | Mississauga | $334K |
| Ostomy Halifax Society | Windsor Junction | $126K |
| Ostomy Hamilton | Hamilton | $17K |
| Ostomy Manitoba Association Inc. | Winnipeg | $65K |
| Ostomy Newfoundland & Labrador | MT Pearl | $9,054 |
| Ostomy Toronto Corporation | Toronto | — |
| Osu Children's Library Fund | Canmore | $242K |
| Osung Presbyterian Church | Scarborough | $26K |
| Ota Education Foundation | Toronto | $235K |
| OTC Community Association | Halifax | $3.1M |
| Other Sights for Artists' Projects Association | Vancouver | $417K |
| Otherhalf-Chinese Stem Cell Initiative | North York | $10K |
| Othman Bin Affan Islamic Society | Vancouver | $162K |
| Otis Cemetery Inc | Barony | $12K |
| Otis Grant & Friends Foundation | Dollard-Des-Ormeaux | $83K |
| Oto-Wa Taiko Group | Ottawa | $32K |
| Otonabee Congregation of Jehovah's Witnesses Peterborough Ontario | Peterborough | — |
| Otonabee - South Monaghan Public Library | Keene | $302K |
| Otra Fe Association for Food Security and Community Development in Western El Salvador | West Lorne | $29K |
| Ottawa All Nations Church | Gloucester | $1.1M |
| Ottawa Amitabha Buddhist Society of Canada | Vernon | $92K |
| Ottawa Arts Council | Ottawa | $382K |
| Ottawa Baptist Association / L'Association Baptiste d'Ottawa | Nepean | $11K |
| Ottawa Biosphere Eco-City | Kanata | $55 |
| Ottawa Bird Count | Ottawa | $1 |
| Ottawa Bluesfest | Ottawa | $25.3M |
| Ottawa Buddhist Society | Nepean | $16K |
| Ottawa-Bytown Rotary Club (Service Fund) Inc. | Ottawa | $3,100 |
| Ottawa C G I T Committee | Ottawa | $51K |
| Ottawa-Carleton Association for Persons With Developmental Disabilities | Ottawa | $38M |
| Ottawa-Carleton District School Board | Nepean | $1.3B |
| Ottawa-Carleton Lifeskills Inc. | Ottawa | $19.9M |
| Ottawa Carleton Puppeteers for Kids on the Block | Ottawa | — |
| Ottawa Carleton Wheelchair Sports Association Inc. | Ottawa | $64K |
| Ottawa-Carleton Wildlife Centre Inc. | Ottawa | $843K |
| Ottawa Catholic Child CARE Corporation | Nepean | $18.8M |
| Ottawa Catholic District School Board | Nepean | $779.9M |
| Ottawa Chamber Orchestra | Ottawa | $24K |
| Ottawa Chapter Children's International Summer Villages (canada) Inc | Ottawa | $13K |
| Ottawa Chevra Kadisha | Ottawa | $232K |
| Ottawa Children's Choir | Ottawa | $375K |
| Ottawa Chinese Bible Church | Ottawa | $327K |
| Ottawa Chinese-Canadian Heritage Centre | Ottawa | — |
| Ottawa Chinese-Canadian Heritage Foundation | Ottawa | — |
| Ottawa Chinese Community Service Centre | Ottawa | $3.6M |
| Ottawa Chinese Language School Inc. | Ottawa | $12K |
| Ottawa Choral Society | Ottawa | $213K |
| Ottawa Christadelphian Ecclesia | Kanata | $4,474 |
| Ottawa Christian Counselling Service Association | Nepean | $315K |
| Ottawa Christian Reformed Campus Chaplaincy | Nepean | $137K |
| Ottawa Christian School Association | Ottawa | $2.9M |
| Ottawa Christian Tabernacle | Vanier | $130K |
| Ottawa Church of God | Ottawa | $400K |
| Ottawa Climate Action Fund | Ottawa | $0 |
| Ottawa Coalition To End Violence Against Women | Ottawa | $695K |
| Ottawa Community Church | North York | $281K |
| Ottawa Community Concert Band | Nepean | $11K |
| Ottawa Community Foundation | Ottawa | $67.3M |
| Ottawa Community Immigrant Services Organization/organisme Communautaire des Services aux Immigrants d'Ottawa | Ottawa | $10.4M |
| Ottawa Community Loan Funds / Fonds d'emprunt communautaire d'Ottawa | Ottawa | $1.8M |
| Ottawa Cursillo Movement | Ottawa | $21K |
| Ottawa Dance Directive | Ottawa | $363K |
| Ottawa Dog Rescue | Nepean | $166K |
| Ottawa Dominicans Or Friars Preachers les Dominicains Ou Freres Precheurs d'Ottawa | Montreal | $10.6M |
| Ottawa Dominicans Or Friars Preachers les Dominicains Ou Freres Precheurs d'Ottawa | Ottawa | $143K |
| Ottawa Dragon Boat Foundation | Nepean | $272K |
| Ottawa Evangelical New Testament Assembly | Ottawa | $32K |
| Ottawa Field Naturalists' Club | Ottawa | $170K |
| Ottawa First Responders Foundation | Woodlawn | $214K |
| Ottawa Folk Festival | Ottawa | $3.6M |
| Ottawa Foyers Partage | Ottawa | $7.7M |
| Ottawa Friends of Tibet | Ottawa | $31K |
| Ottawa Fringe Festival | Ottawa | $902K |
| Ottawa Gatineau Youth Foundation | Ottawa | — |
| Ottawa Gospel Church / Eglise Evangelique d'Ottawa | Ottawa | $301K |
| Ottawa Heart Institute Research Corporation-Corporation de Recherches de l'institut de Cardiologie d'ottawa | Ottawa | $40.3M |
| Ottawa Hebrew Free Loan Association | Ottawa | $36K |
| Ottawa Highland Dancing Association (ohda) | Nepean | — |
| Ottawa Horticultural Society | Ottawa | $21K |
| Ottawa Hospital Research Institute/Institut de recherche de l'hopital d'Ottawa | Ottawa | $146.1M |
| Ottawa-Hull Cambodian Buddhist Association Inc. | Stittsville | $47K |
| Ottawa Humane Society | Ottawa | $14.8M |
| Ottawa Independent Film Festival | Stittsville | $22K |
| Ottawa Independent Living Resource Centre | Ottawa | $219K |
| Ottawa Inner City Health Inc. | Ottawa | $15.6M |
| Ottawa Innercity Ministries | Ottawa | $829K |
| Ottawa Integrative Cancer Centre Foundation | Toronto | — |
| Ottawa Inter Community Buddhist Society | Ottawa | $59K |
| Ottawa Interfaith Spiritualist Church | Nepean | $17K |
| Ottawa Islamic School | Ottawa | $3M |
| Ottawa Japanese Cultural Centre | Nepean | $49K |
| Ottawa Jazz Festival Inc. | Ottawa | $3.6M |
| Ottawa Jewish Historical Society | Ottawa | $25K |
| Ottawa Kitten Rescue | Nepean | $162K |
| Ottawa Korean Community School | Gloucester | — |
| Ottawa Korean New Hope Church | Ottawa | $83K |
| Ottawa Korean Presbyterian Church | Ottawa | $135K |
| Ottawa Little Theatre Inc. | Ottawa | $1.6M |
| Ottawa Live Arts Community (OLAC) | Ottawa | $23K |
| Ottawa Lutheran Refugee Sponsorship Committee Helga Jaakkima | Ottawa | $20K |
| Ottawa Mandarin Alliance Church of The Christian and Missionary Alliance in Canada | Ottawa | $319K |
| Ottawa Mandarin Wesleyan Church | Kanata | $93K |
| Ottawa Mennonite Church | Ottawa | $555K |
| Ottawa Messianic Fellowship | Ottawa | $95K |
| Ottawa Modern Jewish School | Ottawa | $79K |
| Ottawa Montessori School/ecole Montessori d'Ottawa | Ottawa | $9.2M |
| Ottawa Monthly Meeting Religious Society of Friends Quakers | Ottawa | $117K |
| Ottawa Muslim Cemetery Inc. | Ottawa | $1.7M |
| Ottawa Muslim Community Services | Ottawa | $172K |
| Ottawa Neighbourhood Scientific Research Solutions | Gloucester | $149K |
| Ottawa Network for Borderline Personality Disorder/Le réseau d'Ottawa pour le trouble de personnalité limite | Ottawa | $29K |
| Ottawa Network for Education | Ottawa | $5M |
| Ottawa Ostomy Support Group | Nepean | $829 |
| Ottawa Paw Pantry | Ottawa | $40K |
| Ottawa Peace and Environment Resource Centre | Ottawa | $415K |
| Ottawa Peace Foundation | Nepean | — |
| Ottawa Pet Rat Rescue | Nepean | $18K |
| Ottawa Power Wheelchair Hockey League (OPWHL) | Nepean | $41K |
| Ottawa Public Library Board | Ottawa | $61.4M |
| Ottawa Rape Crisis Centre | Ottawa | $1.2M |
| Ottawa Region Bulgarian Foundation Inc. | Ottawa | $23K |
| Ottawa Regional Cancer Foundation/fondation du Cancer de la Region d'Ottawa | Ottawa | $4.2M |
| Ottawa Regional Science Fair | Gatineau | $38K |
| Ottawa Regional Youth Choir Society | Ottawa | $70K |
| Ottawa River of Life Christian Church | Ottawa | $386K |
| Ottawa Riverkeeper Inc. | Ottawa | $1.9M |
| Ottawa Rotary Club Children's Foundation | Ottawa | $11K |