| MBS Scaffolding Limited | Construction | 2020 |
| Mccarey Simmonds Limited | Construction | 2005 |
| MCG Management Services Limited | Construction | 2017 |
| Mcgirl Lees Limited | Hospitality | 2009 |
| Mdap Developments Limited | Construction | 2022 |
| Medialon Ltd | Information & communication | 2019 |
| Megalith Enterprises Limited | Construction | 1993 |
| Merc Media Limited | Professional & scientific | 2020 |
| Merci Ange Limited | Manufacturing | 2025 |
| MGI Architecture Limited | Professional & scientific | 2013 |
| Michael Gillies and Co Limited | Professional & scientific | 2016 |
| Michael P. Jones Construction Management Limited | Administrative & support | 2015 |
| Milestone Awards UK Ltd. | Wholesale & retail | 2016 |
| Miliam Limited | Construction | 2008 |
| Mill Logistics Solutions Limited | Transport & logistics | 2022 |
| Millbrook Land Developments Limited | Real estate | 2006 |
| Milne Limited | Real estate | 2021 |
| MJ Handling Limited | Transport & logistics | 2025 |
| Mobile Tyres Limited | Wholesale & retail | 2011 |
| Molyneux Rose Limited | Real estate | 1983 |
| Molyneux Rose Limited Liability Partnership | | 2005 |
| Moneypenny Enterprises Limited | Real estate | 2006 |
| Morettis Limited | Real estate | 2003 |
| Mount Sound Services Limited | Information & communication | 2025 |
| MP Legal Limited | Administrative & support | 2006 |
| MPA Electrical and Data Ltd | Construction | 2021 |
| Mprom Limited | Professional & scientific | 2009 |
| MTD Express Ltd | Information & communication | 2019 |
| Musicvideoondemand Limited | Information & communication | 2019 |
| MVN Structural Design Limited | Professional & scientific | 2018 |
| My Brakes Don’T Work Limited | Professional & scientific | 2025 |
| My Gleaming Wheels Limited | Wholesale & retail | 2024 |
| My Skin Doctor Limited | Health & social care | 2018 |
| Neale Boys Investments Limited | Real estate | 2016 |
| Neptek Limited | Manufacturing | 2022 |
| Neurithmetic Limited | Education | 2023 |
| Neurosynq Consulting Limited | Health & social care | 2015 |
| New Energy Hub Ltd | Hospitality | 2020 |
| Nextgen Plumbing Supplies Ltd | Wholesale & retail | 2025 |
| Nicco Fuel Ltd | Wholesale & retail | 2024 |
| Nnergy Investments (UK) Ltd | Extraterritorial | 2010 |
| Nordstar Property Company Limited | Real estate | 1982 |
| North ASH (Horsham) Managements Limited | Households | 1974 |
| Novatti Technologies Ltd | Information & communication | 2016 |
| November Securities Limited | Construction | 1993 |
| NQ Capital Limited | Professional & scientific | 2026 |
| Nurture Professional Services Marketing Ltd. | Professional & scientific | 2017 |
| NYB (UK) Ltd | Wholesale & retail | 2024 |
| Oaklands Estate Management Co. Limited | Households | 1997 |
| Old Dairy BN44 Limited | Real estate | 2015 |
| Old Helyers Farm Ltd | Arts & recreation | 2020 |
| Olivia Eyebrows Limited | Other services | 2019 |
| Olwen House Letting Limited | Real estate | 2017 |
| One Stop Computer Store (Billingshurst) Limited | Other services | 2013 |
| Onshore Developments Ltd | Construction | 2020 |
| Onshore Group Ltd | Real estate | 2023 |
| Onshore Lettings Limited | Real estate | 2021 |
| Onwrd Ltd | Information & communication | 2025 |
| Optimise Design Services Ltd | Professional & scientific | 2005 |
| Option Energy Solutions Ltd | Construction | 2014 |
| Orbit 21 Consulting Limited | Professional & scientific | 2019 |
| Organic Arable Marketing Company Limited | Agriculture & fishing | 1999 |
| Other Finger Films Limited | Information & communication | 2015 |
| Otherpay Limited | Information & communication | 2020 |
| Outdoor Installations Limited | Professional & scientific | 2007 |
| Own Imagination Ltd | Information & communication | 2018 |
| P B M Exteriors Limited | Construction | 2005 |
| P.D.B. Engineering Services Limited | Manufacturing | 1994 |
| Park Mount Lodge Limited | Households | 2005 |
| Party Snail Limited | Information & communication | 2024 |
| Partytom Limited | Arts & recreation | 2014 |
| Paul Kennedy IT Test Limited | Information & communication | 2004 |
| Paul Thurlby Limited | Professional & scientific | 2026 |
| Paws for Tea Limited | Hospitality | 2021 |
| Pelyma Limited | Administrative & support | 2014 |
| Penhill Mews Management Limited | Households | 2008 |
| Penlands Properties Ltd | Real estate | 2020 |
| Pentagon Instruments Limited | Manufacturing | 1974 |
| Pepperscombe Farm Ltd | Hospitality | 2017 |
| Peregrine Scaffolding Ltd | Construction | 2017 |
| Philips Surveyors LLP | | 2012 |
| Phillips Plant Hire Limited | Administrative & support | 2012 |
| Phillips Scaffolding Limited | Construction | 2011 |
| Phoslock Water Solutions (UK) Limited | Professional & scientific | 2006 |
| Physiotherapy Services Limited | Health & social care | 1997 |
| Pick UP Languages Limited | Education | 2013 |
| Pickleball Escapes Limited | Administrative & support | 2025 |
| Picobit Ltd | Information & communication | 2020 |
| Poppy Sussex Limited | Professional & scientific | 2024 |
| Portrealm Limited | Real estate | 1983 |
| Positive Labs Ltd | Health & social care | 2022 |
| Poulet Vous Limited | Extraterritorial | 2010 |
| Powel International Limited | Professional & scientific | 1973 |
| Powerbase Building Services Limited | Construction | 2003 |
| PR23 Limited | Information & communication | 2005 |
| Press Red Limited | Arts & recreation | 2008 |
| Prestige Origin Media Limited | Information & communication | 2026 |
| Price Surveyors Limited | Real estate | 2009 |
| Prime Nights Property Management Ltd | Real estate | 2026 |
| Prime Securities Limited | Construction | 1959 |