| Newstep Two Ltd | Hospitality | 2019 |
| Newton Paisley Ltd | Manufacturing | 2015 |
| NFL Ltd | Construction | 2022 |
| Nice and Tidy Services Ltd | Construction | 2026 |
| Nice Music Ltd | Arts & recreation | 2025 |
| Niche Radio Group Ltd | Information & communication | 2025 |
| Niche VFX Limited | Administrative & support | 2009 |
| Nicholas James Hair Limited | Administrative & support | 2006 |
| Nick Arundel Productions Limited | Professional & scientific | 2023 |
| Nick Fehnle Designs Ltd | Professional & scientific | 2017 |
| Nina Maklin Creative Studio Limited | Professional & scientific | 2014 |
| Ninety One Logistics UK Ltd | Administrative & support | 2014 |
| Ninety One Recruitment Solutions Ltd | Administrative & support | 2017 |
| Ninety One Solutions Ltd | Construction | 2016 |
| Nishi Development Ltd | Professional & scientific | 2019 |
| Nitv Management Ltd | Information & communication | 2021 |
| NJT Technical Ltd | Professional & scientific | 2022 |
| NLK Property Management Limited | Administrative & support | 2014 |
| NO. 1 Gloucester Road Management Company Limited | Households | 2025 |
| NO.1WHITSTABLE Ltd | Hospitality | 2024 |
| NOBEL8 Ltd | Financial services | 2022 |
| Nordin Medical Services Limited | Health & social care | 2010 |
| North Beach Consulting Ltd | Information & communication | 2017 |
| North Kent Dental Laboratories Limited | Health & social care | 1970 |
| North Lane Residents Company Limited | Households | 2011 |
| North Quay Trading Limited | Manufacturing | 1996 |
| Northover Cars Limited | Wholesale & retail | 2006 |
| Northwood Partners Ltd | Professional & scientific | 2025 |
| Norwegin Holdings Limited | Manufacturing | 2020 |
| NOT the PIG Ltd | Professional & scientific | 2025 |
| NS Professional Placement Limited | Administrative & support | 2024 |
| NST Property Ltd | Construction | 2024 |
| Nuanced Psychology Ltd | Health & social care | 2025 |
| Number Eight Canterbury Limited | Real estate | 2023 |
| Number Nine Castle Street CIC | Hospitality | 2024 |
| Nursery Gardens Limited | Extraterritorial | 2020 |
| Nurture Nature Ltd | Administrative & support | 2012 |
| NVR Heating and Plumbing Services Limited | Construction | 2020 |
| O.N.N Training and Consultancy Services Limited | Other services | 2017 |
| Oakdane Limited | Construction | 1983 |
| Oakland Contractors Limited | Construction | 2020 |
| Oakley Holdings Limited | Real estate | 2017 |
| Oakmore Green Limited | Administrative & support | 2018 |
| Oakwood Tutors Ltd | Education | 2020 |
| Oast Developments Limited | Construction | 2006 |
| Oath Studio Ltd | Arts & recreation | 2024 |
| Object Consultancy Ltd | Construction | 2022 |
| Occasions of Herne Bay Limited | Administrative & support | 2002 |
| OCD Project Management Limited | Construction | 2023 |
| Ocean Fever Ltd | Administrative & support | 2013 |
| Ocean Property Trading Company Limited | Real estate | 2024 |
| Octangular Consulting Limited | Administrative & support | 2022 |
| Octangular Limited | Real estate | 2021 |
| Octo Building Contractors Ltd | Construction | 2017 |
| Odin (Wessex) Ltd | Administrative & support | 2019 |
| Odin Group Ltd | Administrative & support | 2024 |
| Odin Militaria Ltd | Administrative & support | 2026 |
| Odin Tactical Ltd | Administrative & support | 2019 |
| Odins Warrior Halls Ltd | Administrative & support | 2024 |
| OFF the Grid Offices Limited | Professional & scientific | 2017 |
| OFF the Wall Club Limited | Real estate | 2022 |
| OGC Maintenance Limited | Construction | 2002 |
| Oinio Limited | Information & communication | 2025 |
| OK Property Maintenance Ltd | Real estate | 2024 |
| Old Bakery Mews Residents Limited | Households | 1998 |
| Old Vicarage Property Association Limited | Households | 1976 |
| Oliver Commissioning and Controls Ltd | Professional & scientific | 2014 |
| Omes Installations Ltd | Construction | 2021 |
| ON Clouds Limited | Information & communication | 2008 |
| Onboard Intelligence Ltd | Professional & scientific | 2025 |
| One and Only Accounts Limited | Professional & scientific | 2025 |
| ONE150 Limited | Wholesale & retail | 2021 |
| ONE160 Limited | Wholesale & retail | 2025 |
| ONE180 Limited | Wholesale & retail | 2024 |
| ONE190 Limited | Wholesale & retail | 2025 |
| Onebuildingco Ltd | Construction | 2026 |
| Opal Design Management Ltd | Professional & scientific | 2012 |
| Operational Edge Limited | Professional & scientific | 2002 |
| Optima Flooring Limited | Construction | 2025 |
| Optima Resin Limited | Administrative & support | 2024 |
| Orec Limited | Health & social care | 2010 |
| Orielo Ltd | Information & communication | 2025 |
| Original Bear Media Ltd | Information & communication | 2013 |
| Origins Solutions Ltd | Administrative & support | 2023 |
| Orisans Bakery Ltd | Manufacturing | 2026 |
| Osang Financial Planning Ltd | Financial services | 2019 |
| Osprey Corporation Limited | Professional & scientific | 1985 |
| Ostrea Consultancy Limited | Professional & scientific | 2026 |
| OTQ Ltd | Administrative & support | 2014 |
| Ovenstone Pizza Limited | Hospitality | 2025 |
| Overseas Ltd | Real estate | 2022 |
| Owen Paulo Legal Limited | Professional & scientific | 2022 |
| Owens Real Estate Ltd | Real estate | 2022 |
| Own Your Life Writing C.I.C. | Health & social care | 2025 |
| Oyoo Earth Company Ltd | Administrative & support | 2015 |
| Oyster Bay Court (Whitstable) Management Company Limited | Households | 2012 |
| Oyster Cars (UK) Ltd | Wholesale & retail | 2018 |
| Oyster Mews (Whitstable) Management Company Limited | Households | 2003 |
| Oyster Pearl Bar & Restaurant Limited | Hospitality | 2018 |
| Oyster Property Surveyors Ltd | Professional & scientific | 2018 |