| Jonori Ltd | Information & communication | 2026 |
| Jorge Radis PM Limited | Professional & scientific | 2016 |
| Joseliz Limited | Professional & scientific | 2010 |
| Josh Ingram Decorating Ltd | Construction | 2024 |
| Joshua LEE Ltd | Arts & recreation | 2022 |
| Jp.Physiotherapy Ltd | Other services | 2024 |
| JPC Group Ltd | Construction | 2020 |
| JPS Stationers Limited | Wholesale & retail | 2011 |
| JR Base Solutions Limited | Administrative & support | 2016 |
| Jrbe Limited | Real estate | 2022 |
| JS Future Lettings Limited | Real estate | 2021 |
| JSK Products and Services Ltd | Information & communication | 2009 |
| JSK Realty Limited | Real estate | 2018 |
| JTM Heating Ltd | Construction | 2023 |
| Jtm&V Construction Ltd | Construction | 2022 |
| JTN Training Ltd | Education | 2022 |
| Julia Graham Ltd | Arts & recreation | 2015 |
| June FOG Limited | Professional & scientific | 2008 |
| Juntos Holding Limited | Financial services | 2025 |
| JUS MAS Ltd | Arts & recreation | 2024 |
| Justine Inglis Hotel Consultancy Limited | Professional & scientific | 2014 |
| K B Wilde Consulting Limited | Professional & scientific | 2007 |
| K S T D Limited | Real estate | 1991 |
| K Whelan Ltd | Wholesale & retail | 2021 |
| K.D. Kirby Electrical Services Ltd | Construction | 2019 |
| K2 FX Ltd | Professional & scientific | 2023 |
| Kacper Cars Limited | Administrative & support | 2025 |
| Kaden Plastics Limited | Manufacturing | 2009 |
| KAE Limited | Administrative & support | 2005 |
| Kaleido JKR Limited | Wholesale & retail | 2025 |
| Kanaka IT Solutions Limited | Information & communication | 2016 |
| Kare Physio Services Ltd | Health & social care | 2022 |
| Karl Harrison Landscapes Limited | Administrative & support | 2020 |
| KAS Property Investment Limited | Real estate | 2020 |
| Kash 4 Kars Limited | Wholesale & retail | 2022 |
| Kashmir Lamb Rush Ltd | Wholesale & retail | 2024 |
| Kasnet Ltd | Wholesale & retail | 2024 |
| Kate Woodward Estate Agent Ltd | Real estate | 2022 |
| Kaylex Electrical Wholesalers and Distributors Ltd | Wholesale & retail | 2009 |
| KB2S Ltd | Extraterritorial | 2009 |
| KBM Accounting Associates Limited | Professional & scientific | 2006 |
| KC Pipelines Ltd | Construction | 2023 |
| KE Architecture (London) Limited | Professional & scientific | 2012 |
| Keane to Develop Limited | Professional & scientific | 2015 |
| Kebab House Chesham Ltd | Hospitality | 2023 |
| Kefo Lettings Limited | Real estate | 2013 |
| Kefo Projects Limited | Construction | 2003 |
| Kenan Devran Ltd | Other services | 2020 |
| Kenmore Astell Ltd | Health & social care | 2025 |
| Kenmore Care Dynamics Limited | Health & social care | 2022 |
| Kenmore Care Holding Ltd | Health & social care | 2017 |
| Kenmore Ferndown Limited | Health & social care | 2023 |
| Kenmore Glendale Ltd | Health & social care | 2024 |
| Kenmore Group Properties Ltd | Real estate | 2025 |
| Kenmore Hamilton Park Limited | Health & social care | 2024 |
| Kenmore Management Ltd | Professional & scientific | 2022 |
| Kenmore Resthaven Ltd | Health & social care | 2025 |
| Kennedy Funnell Limited | Professional & scientific | 2012 |
| Kenote Ltd | Administrative & support | 2020 |
| Kenyon & Sons Ltd | Financial services | 2021 |
| Keypart International Limited | Financial services | 2022 |
| Keypart Limited | Administrative & support | 2004 |
| Khakis Blues N 2S Limited | Wholesale & retail | 2005 |
| Kiddies Cove Day Nursery Ltd | Education | 2021 |
| Kiddies Cove Holdings Ltd | Administrative & support | 2024 |
| Kiddleydivey Limited | Arts & recreation | 1999 |
| Kids GET Ahead Limited | Education | 2011 |
| Kiernan Nurseries Limited | Education | 2024 |
| Kikada Limited | Real estate | 2024 |
| Kilrock Products Ltd | Manufacturing | 1994 |
| Kimblewick Feeds Ltd | Wholesale & retail | 2012 |
| Kincol Limited | Financial services | 1948 |
| Kinectic Consulting Ltd | Information & communication | 2012 |
| Kingfisher Tapes Limited | Wholesale & retail | 1981 |
| Kingley Vale Group Ltd | Professional & scientific | 2018 |
| Kings ASH Garage Ltd | Wholesale & retail | 2022 |
| Kingshill Furniture Limited | Construction | 2011 |
| Kingshill Private Hire Limited | Transport & logistics | 2017 |
| Kinsey Management Services Limited | Professional & scientific | 2019 |
| Kirkhead Legal Consulting Limited | Professional & scientific | 2009 |
| Kirstie Walker-Poole Ltd | Professional & scientific | 2025 |
| Klamer Investments Ltd | Real estate | 2021 |
| Klasiena Slaney Limited | Professional & scientific | 2008 |
| Klass Kuts (Chesham) Limited | Other services | 2017 |
| Klermon LP | | 2024 |
| KMJ IT Solutions Ltd | Information & communication | 2017 |
| KMJ Properties Ltd | Real estate | 2023 |
| Kmmc Commercial Limited | Professional & scientific | 2025 |
| Knhaq Properties Ltd | Real estate | 2022 |
| Knight Executive Research Limited | Administrative & support | 2014 |
| Knockout Clean Ltd | Wholesale & retail | 2023 |
| Knowledgesmith Limited | Education | 2018 |
| Komputer Consultancy Services Limited | Information & communication | 1998 |
| KRA Construction Services Ltd | Construction | 2021 |
| Krafted Interiors Ltd | Construction | 2013 |
| Kris Kopy Ltd | Information & communication | 2014 |
| Kscr Investments Ltd | Real estate | 2022 |
| KSR Premier Ltd | Other services | 2022 |
| Kubb Ltd | Construction | 2018 |
| Kuber Capital Ltd | Financial services | 2019 |