- Observis
- Ocean View Games
- Oddrok
- OGOship
- oik.AI
- Oikee
- Oinride
- OiOi Smart Space
- Olakino
- Olento Life
- Olet Ihana!
- Olo
- Omakirja
- Omegawave
- Omply Health
- Onbone
- Oncarbon
- One1
- One Click LCA
- One Hour Method
- ONEiO
- OneMind Dogs
- OneStream
- Onesys Medical
- Online Dynamics
- Onni Care
- On-Time
- Ookoohko
- Oppi AI
- Oppidoo
- Oppifi
- Optitune
- OptiWatti
- Optogear
- Optomed
- Order Of Meta
- Orelo
- Origin by Ocean
- Ori Solution
- Orxter
- Otometri
- Ouman
- Oura
- Owatec
- OYOs Games
