- Oadby - 3 companies
- Oak Drive - 1 company
- Oak Ridge - 1 company
- Oakham - 29 companies
- Oakhanger - 1 company
- Oakley - 1 company
- Oban - 6 companies
- Off Atkinson Street, - 1 company
- Off Cambridge Road - 1 company
- Okehampton - 20 companies
- Old Buckenham - 1 company
- Old Dalby - 1 company
- Old Street - 1 company
- Old Trafford - 2 companies
- Old Woking - 1 company
- Oldbury - 65 companies
- Oldham - 244 companies
- Oldmeldrum - 2 companies
- Ollerton - 1 company
- Olney - 15 companies
- Olton - 1 company
- Omagh - 12 companies
- Ongar - 21 companies
- Ontario - 7 companies
- Orkney - 1 company
- ormskirk - 43 companies
- Orpington - 73 companies
- Orston - 1 company
- Orton Southgate - 2 companies
- Osgathorpe - 1 company
- Osset - 1 company
- Ossett - 37 companies
- Ostrów Wielkopolski - 1 company
- Oststeinbek - 1 company
- Oswaldtwistle - 2 companies
- Oswestry - 32 companies
- Otley - 16 companies
- Ottery St. Mary - 1 company
- Oulton - 1 company
- Overath-Vilkerath - 1 company
- Overton - 1 company
- Owthorpe - 1 company
- Oxford - 128 companies
- Oxfordshire - 56 companies
- Oxon - 28 companies
Towns 1 to 45 | Page 1 of 2
