| Kerrera Partners Ltd | Financial services | 2019 |
| Key Hill Village (Hockley) Limited | Real estate | 2021 |
| Key Hill Village Limited | Real estate | 2018 |
| Keyblue Consulting Ltd | Professional & scientific | 2016 |
| Keyring Records Ltd | Wholesale & retail | 2024 |
| KGR Concierge Services Ltd | Real estate | 2012 |
| KGR Media Services Ltd | Professional & scientific | 2011 |
| Kids Capers Limited | Health & social care | 2012 |
| Kiki's Pet House Limited | Wholesale & retail | 2020 |
| Kikptstudios Limited | Other services | 2008 |
| Kilnwood Consulting Limited | Professional & scientific | 2010 |
| KIM Taylor Cards Limited | Wholesale & retail | 2020 |
| Kimoran Consulting Limited | Administrative & support | 2022 |
| Kind & Care Taxis Ltd | Transport & logistics | 2025 |
| King's Court (Cuckfield) Limited | Households | 1999 |
| Kingpost Carpentry Limited | Construction | 2021 |
| Kings Hill Equestrian Ltd | Agriculture & fishing | 2019 |
| Kingsley Green Limited | Extraterritorial | 2003 |
| Kingsmead Infection Prevention Consultancy Limited | Administrative & support | 2020 |
| Kingston Consulting Global Limited | Administrative & support | 2014 |
| Kingston Consulting Limited | Professional & scientific | 1995 |
| Kingswood Shetlands & Friends AAT CIC | Other services | 2020 |
| Kins Photographic Ltd | Professional & scientific | 2024 |
| Kipper Creative Limited | Other services | 2007 |
| Kirby Hodgson Collective Ltd | Education | 2026 |
| Kirkgate Street Limited | Construction | 2022 |
| Kiskadee Services Ltd | Professional & scientific | 2015 |
| Kiss Burger Limited | Hospitality | 2024 |
| Kitchen Repairs & Sales Limited | Manufacturing | 2012 |
| Kitman Limited | Information & communication | 2010 |
| Kitsquare Limited | Professional & scientific | 1973 |
| Kitts Campsite Ltd | Hospitality | 2024 |
| Kittsmead Properties Limited | Real estate | 2025 |
| Kivee Group Limited | Professional & scientific | 2025 |
| Kj&J Enterprise Ltd | Administrative & support | 2017 |
| KJF IT & Services Consultancy Limited | Information & communication | 2020 |
| KJM Associates Limited | Professional & scientific | 2012 |
| KK News Ltd | Wholesale & retail | 2020 |
| KKA Consulting Ltd | Administrative & support | 2011 |
| KLA Architects Limited | Professional & scientific | 2008 |
| KLA Financial Planning Limited | Administrative & support | 2021 |
| KM Architecture Limited | Professional & scientific | 2020 |
| KMG Electrical Services Limited | Construction | 2010 |
| Kmjay Consultancy Limited | Professional & scientific | 2020 |
| Kmjm Consulting Limited | Professional & scientific | 2026 |
| Kmndnt Limited | Wholesale & retail | 2021 |
| KMP Services Ltd | Professional & scientific | 2015 |
| Knaq Limited | Other services | 2019 |
| Knight Recruitment Limited | Administrative & support | 1999 |
| Knight Rentals Limited | Real estate | 1957 |
| Know Howe ERP Solutions Ltd | Professional & scientific | 2021 |
| Knowbrayner Ltd | Professional & scientific | 2010 |
| Knox Locks Limited | Other services | 2008 |
| Kobayashi Maru Engineering Ltd | Professional & scientific | 2022 |
| Koda Brewing Company Ltd | Manufacturing | 2025 |
| Koehl UK Ltd | Manufacturing | 2018 |
| Koin Sussex Ltd | Wholesale & retail | 2024 |
| Koios Ltd | Information & communication | 2025 |
| Kompak Property Ltd | Real estate | 2025 |
| Komura Lambden Limited | Information & communication | 2016 |
| Konbook Limited | Real estate | 1996 |
| Konnect With Sport Ltd | Education | 2024 |
| Koru Home Solutions Limited | Real estate | 2023 |
| Kosta Capital Construction Ltd | Administrative & support | 2017 |
| KPS Build Limited | Construction | 2022 |
| KPS Business Park Limited | Real estate | 1986 |
| KPS Composting Services Limited | Water & waste | 2000 |
| Kpulse Ltd | Health & social care | 2022 |
| KR Developments LLP | | 2025 |
| Kraus Interiors Ltd | Manufacturing | 2025 |
| Krystal TIA Property Limited | Real estate | 2016 |
| KS Group Business Services Ltd | Wholesale & retail | 2023 |
| KST Fiduciary Services Limited | Administrative & support | 2013 |
| Kudos 38 Limited | Professional & scientific | 2013 |
| Kumon Crawley West LLP | | 2023 |
| Kusum Enterprise Ltd | Wholesale & retail | 2021 |
| Kuti Properties Limited | Real estate | 2024 |
| KW Construction (South East) Limited | Construction | 2014 |
| L Camille Ltd | Real estate | 2022 |
| L Dalmon Building Limited | Construction | 2024 |
| L R Smith Consulting Engineers Limited | Professional & scientific | 2017 |
| L T Building Services Sussex Ltd | Construction | 2016 |
| L.A.Exchange Ltd | Wholesale & retail | 2013 |
| L.Neshan H&T Ltd | Health & social care | 2022 |
| LA Plumbing Ltd | Construction | 2024 |
| Lacewing Media Limited | Professional & scientific | 2021 |
| Laisa Limited | Professional & scientific | 2022 |
| LAM Matters Limited | Professional & scientific | 2014 |
| Lamb Holdings Limited | Extraterritorial | 1996 |
| Lamoureux Consulting Limited | Information & communication | 2013 |
| Lamper's Luxuries Ltd | Construction | 2024 |
| Lancap Limited | Information & communication | 2018 |
| Land Advisory Limited | Administrative & support | 2020 |
| Land Invest 5 Limited | Real estate | 2025 |
| Land-Smith Property Ltd | Construction | 2025 |
| Lande Consultancy Services Ltd | Professional & scientific | 2021 |
| Landscapes Limited | Administrative & support | 2005 |
| Langabeer Holdings Ltd | Professional & scientific | 2016 |
| Langleycourt Properties Limited | Real estate | 1996 |
| Lapwing Associates Ltd | Professional & scientific | 2025 |