- Onyx Make Up Glasgow
- Onyx Timer - Hands Free, Voice Controlled, Talking Exercise Timer
- OOB life
- OOLER
- Ooly: Configuration App
- Ooly: Stories
- Oomph: Weight Loss & Strength
- Ooooo
- Oopsie Heroes
- Oorenji: Science & Nutrition
- Oorja Wheel
- OoSnap
- OOVA
- Oozbein
- OP Care
- Op.Dr. Banu Çiftçi & Hamilelik
- Opal: Screen Time for Focus
- Opale
- OPCenters
- Opel Mobile Guardian
- Open: Breathwork + Meditation
- Open Area Dance
- Open Diabetes BG Charts/Graphs
- Open Fitness
- Open Food Facts - Product Scan
- Open Mat
- Open Padel
- Open Water Adventures
- Open2Care
- OpenBox Athletics
- Symptom Tracker - OpenCare
- OpenDance Academy
- OpenField Plus Live
- Openground Mindfulness
- OpenMind – EFT, mediteer, adem
- MySesame
- Opensport24
- OpenSports - your sport groups
- OpenTeleRehab
- Opera Moema
- OPERAS Arthritis
- Operation Reach Out
- Operation Smile
- Operation Transformation
- Operationskollen
- OperaVR Home Therapy
- Operationskollen
- OperaVR Home Therapy
- Opiah Cosmetics
- OPIE Anywhere
- Opificio Emiliano
- Opioids Dosage Conversion
- OpiRescue
- Opium Skin & Beauty
- Oplayer Smart Life
- Oplo
- OPlus .
- Measure your Hikes
- OPO
- Oppositional Defiant D. Test
- Opravdové zdraví
- Opro9 Adult SmartDiaper
- Opro9 SmartDiaper
- OPS Ready
- Opt Health
- Opti Brain
- Opti Calm
- Opti Confidence