| HSC Global Asset Management Limited | Professional & scientific | 2011 |
| Hub (High Street Maidenhead) Management Company Limited | Households | 2003 |
| Hughesflow Plumbing Ltd | Construction | 2025 |
| Huli Huli Retail Limited | Wholesale & retail | 2023 |
| Hunt & Nash Estate Agents Ltd | Real estate | 2008 |
| Hyper Modernity Ltd | Information & communication | 2022 |
| I Love Coffee Roasting UK Ltd | Education | 2023 |
| I ME Mine Design Limited | Information & communication | 2010 |
| I V R (UK) Limited | Other services | 2006 |
| Ibis Court (Beckenham) Management Company Limited | Households | 2013 |
| Ickenham Park (North) Management Company Limited | Households | 2012 |
| Ickenham Park North (Estate) Management Company Limited | Households | 2012 |
| Icknield Close Management Company Limited | Households | 1981 |
| ICM Properties Limited | Real estate | 2001 |
| Idis Creative Marketing Ltd | Professional & scientific | 2020 |
| Illusive Solutions Ltd | Professional & scientific | 2002 |
| Imber Riverside (East Molesey) Management Company Limited | Households | 2017 |
| Impulsed Labs Ltd | Financial services | 2022 |
| Infinity Construction Products Ltd | Construction | 2024 |
| Initia Limited | Construction | 2012 |
| Inkfiller Ltd | Other services | 2022 |
| Inside the Box Solutions Limited | Construction | 2014 |
| Insidepower Ltd | Wholesale & retail | 2019 |
| Inspiring Reward Ltd | Professional & scientific | 2021 |
| Institute of Vehicle Recovery(The) | Other services | 1984 |
| Intellifocus Ltd | Wholesale & retail | 2024 |
| Inzicht Limited | Other services | 2015 |
| Ismosys Management Limited | Wholesale & retail | 2009 |
| Isobel Cooper Limited | Arts & recreation | 2017 |
| Ison Images Limited | Professional & scientific | 2013 |
| It's Been a Joy Ltd | Administrative & support | 2024 |
| It's the Business Limited | Extraterritorial | 1998 |
| Itech Gaming Limited | Arts & recreation | 2017 |
| Ivaldi Ltd | Arts & recreation | 2025 |
| Iver Flowerland Limited | Wholesale & retail | 1984 |
| IVR Training Services Limited | Professional & scientific | 1998 |
| J H P Electrical Services Limited | Construction | 2005 |
| J.F. Heppelthwaite Limited | Construction | 1978 |
| Jack POP Events Ltd | Administrative & support | 2023 |
| Jackson Court Management Company Ltd | Households | 1998 |
| Jacob & Logan Court RTM Limited | Households | 2011 |
| Jago Design & Manufacturing Limited | Manufacturing | 2007 |
| Jakata Technology Consulting Ltd | Information & communication | 2016 |
| James Ellis Healthcare Limited | Health & social care | 2011 |
| Jameson Group (Leatherhead) Limited | Professional & scientific | 1988 |
| Jane Morgan Management Limited | Professional & scientific | 1990 |
| JBR Management Consulting Ltd | Extraterritorial | 2023 |
| Jcal Holdings Ltd | Financial services | 2026 |
| Jcal Investments Ltd | Real estate | 2026 |
| JDA Consult Ltd | Professional & scientific | 2026 |
| JDS Link Limited | Professional & scientific | 2019 |
| Jehb Services Ltd | Information & communication | 2016 |
| Jennings Fine Art Limited | Wholesale & retail | 2004 |
| JO Cowlin Limited | Administrative & support | 2017 |
| John Walsh London Limited | Wholesale & retail | 2006 |
| Johnstone and Co Financial Services Limited | Financial services | 2019 |
| Jonathan Arron Residential Limited | Real estate | 2005 |
| JPV Construction Ltd | Construction | 2021 |
| JSB Media Services Limited | Arts & recreation | 2012 |
| JWJ Design Limited | Professional & scientific | 2011 |
| Kang Estate Ltd | Real estate | 2023 |
| Karpouzi AI Consultancy Limited | Information & communication | 2025 |
| Kashi House Pictures Limited | Information & communication | 2019 |
| Kate Jackson Architects LLP | | 2015 |
| Kattam Limited | Hospitality | 2017 |
| Kayak Plumbing Limited | Manufacturing | 2011 |
| Kaylex Properties Ltd | Real estate | 2024 |
| KCH Edtech Consulting Ltd | Information & communication | 2025 |
| KEG Craft Beer Ltd | Hospitality | 2018 |
| Kemitel Limited | Professional & scientific | 2009 |
| Kemp Hall Group Ltd | Manufacturing | 2024 |
| Kennet Heath Management (NO.4) Limited | Extraterritorial | 2007 |
| Keswick RD (Putney) Management Co. Limited | Households | 2006 |
| Keydata.Co.Uk Ltd | Extraterritorial | 2026 |
| KHD Management Limited | Households | 2014 |
| Kimber Place (Freehold) Limited | Real estate | 2009 |
| Kimber Place Management Company (Headington) Limited | Real estate | 2008 |
| Kindpride Limited | Real estate | 1997 |
| Kings Hill Park Resmanco Limited | Extraterritorial | 2003 |
| Kingston Road (New Malden) Management Company Limited | Households | 2004 |
| Kinkind Limited | Wholesale & retail | 2019 |
| Kinsale Grange Limited | Real estate | 2004 |
| Kirkwood Mulberry Ltd | Administrative & support | 2017 |
| Kirkwood Property Developments Limited | Financial services | 2017 |
| Kirkwood Property Management Ltd | Real estate | 1999 |
| Kirkwood Residential Ltd | Administrative & support | 2019 |
| Kitchen Company Limited(The) | Administrative & support | 1985 |
| Klaus Design Ltd | Professional & scientific | 2023 |
| Klinitrial Holdings Limited | Financial services | 2013 |
| Klinitrial Limited | Professional & scientific | 2011 |
| KM Holmer Green Management Company Limited | Households | 2021 |
| Komao Luxury Hair Extensions Ltd | Other services | 2020 |
| Kompact Services Ltd | Information & communication | 2023 |
| Kongs Restaurant (Bourne END) Ltd | Hospitality | 2019 |
| Kooki Design Limited | Manufacturing | 2025 |
| KRB Garage Equipment Services Limited | Manufacturing | 2011 |
| Kriscare Ltd | Health & social care | 2016 |
| Kynos Therapeutics Ltd | Professional & scientific | 2020 |
| LA Rose Noire Candles & Soaps Limited | Manufacturing | 2021 |
| Lacey Drive Management Company Limited | Households | 2003 |