- Outdoor+c by Caffi Group
- OUTIN. DESIGN
- Outline Studio 74
- OUTOFBOX
- OUTOFSTOCK
- Outpost
- OutrArquitetura
- outsideIN
- OUTSIDER
- out-sider A/S
- Outsider.Architecture
- Outsource CAD Services
- OUTSTUDIO
- OV-A
- OVA Architetti
- OVACEN
- OVAL
- ovattificio alpino
- Ovattificio Olimpia
- Ovature Studios
- OVD
- OVENTROP
- Oventrop Gmgh & Co. KG
- over
- OVER SRL
- Over the counter Liban
- OVER THE NET
- over, under
- OVERALL
- OVER-ALL
- Overall - Winner
- OverAll Srl
- OverAlls Architecture
- overcar
- Overdrive
- Overeem BV
- Overgaard & Dyrman
- Overgaard & Dyrman Aps
- Overhead s.a.s.
- overland srl
- Overlay Office
- Overlight_ConnectART
- overload engineering
- OVERMAR, SRL
- Overmat Industries B.V.
- overoots_design
- OVERTEK-VERNICIATURA INDUSTRIALE METALLI
- Overtreders W