Bedrift O - Gamle Fredrikstad
- Oldenborgila
- Optimal AS
- Oldenborgila
- Opes AS
- Orval AS
- OneFoot AS
- Onsiteviewer AS
- Oleg Laumakin
- Olav Ødegård
- Optimal Utleie AS
- Osland Consulting
- Okapi Records AS
- Oikos Østfold
- Olavshall SA
- Optima Holding AS
- Olsen Eiendom
- Organisasjonen Plus
- Oppvekstdata V/Bruhn
- Oil Eater AS
- Ottar Weel
- Odd Amundsen
- Omberg Geir
- Opalveien boliger
- Oviba Holding AS
- Olseng Bygg
- Olavesen Eiendom AS
- Oaf Invest AS
- Olastranda Båtforening
- Oe Kiropraktikk AS
- Oliver Travel AS
- Om Data AS Konkursbo
- Om Data AS Konkursbo
- Olanders Recycling Tools AS
- OK Minilager Øra
- Optikon Medisinske Senter DA
- Odd Asbjørn Iglebæk
- Ola Dahl Jensen
- Ordkløveriet Anne Buvik
- Olav Nicolai Mohr
- Oskar Kornelius Emhjellen
- Ole Petter Hansen
- Odd Werner Andersen
- Outcall Solutions Fredrikstad AS Konkursbo
- Outcall Solutions Fredrikstad AS Konkursbo
- Ortofot Eva-Irén Aarum
- OBOS Eiendomsmeglere Fredrikstad Østsiden
- Onyx Industriservice AS Anlegg for Tankbilvask
- Outcall Solutions Hamsa Abdul Kadir Islow
- Orff Grafisk Design Knut-Richard Bangor