| Julee Care Limited | Health & social care | 2015 |
| Jules EXP Agent Ltd | Real estate | 2023 |
| Juniper Business Consulting Limited | Professional & scientific | 2020 |
| Just ASK JOE Ltd. | Professional & scientific | 2023 |
| Just Glamify Ltd | Wholesale & retail | 2026 |
| Justine Harris Ltd | Arts & recreation | 2020 |
| Juuls Ltd | Wholesale & retail | 2012 |
| Jvam Limited | Real estate | 2012 |
| Jvam Opco Limited | Financial services | 2022 |
| JWO Beauty Limited | Manufacturing | 2015 |
| K-Kaps International Ltd | Manufacturing | 2018 |
| K.N.H. Consulting Limited | Professional & scientific | 2010 |
| K5 Spice Limited | Hospitality | 2023 |
| Kabinett 5 Limited | Manufacturing | 2019 |
| Kaglor Limited | Real estate | 2020 |
| Kaici Ltd | Professional & scientific | 2020 |
| Kaler Marketing Limited | Administrative & support | 2020 |
| Kalliope (U.K.) Limited | Administrative & support | 1993 |
| Kallon & Co Group Limited | Construction | 2024 |
| Kanar Engineering Ltd | Construction | 2020 |
| Kane Keogh Commercial Ltd | Construction | 2023 |
| Karani Enterprises Limited | Administrative & support | 2011 |
| Karinas Barber Shop Ltd | Other services | 2026 |
| Karsh Properties Ltd | Real estate | 2018 |
| Katalysis NET Limited | Information & communication | 2000 |
| Katherine Scott Coaching Limited | Administrative & support | 2021 |
| Katie Beard Ltd | Professional & scientific | 2024 |
| Kaya Design and Sign Ltd | Wholesale & retail | 2020 |
| Kbear Inform Limited | Professional & scientific | 2012 |
| Kcdc Design Limited | Information & communication | 2013 |
| Kcpi Limited | Construction | 2017 |
| KE Locations Ltd | Information & communication | 2023 |
| Kead Properties Ltd | Real estate | 2026 |
| Keats House Holdings Limited | Households | 2015 |
| Keith Trodden Projects Ltd | Construction | 2012 |
| Kenilworth Property Investments Ltd | Real estate | 2025 |
| Kennesbourne Court Limited | Households | 1984 |
| Kenwood Construction Limited | Construction | 2008 |
| Kestrix Ltd | Professional & scientific | 2022 |
| Kevin Williams Laser Expert Limited | Information & communication | 2022 |
| Keye Talent Group Ltd | Administrative & support | 2021 |
| Keye Talent Management Ltd | Administrative & support | 2025 |
| Keystone Tech Solutions Limited | Information & communication | 2025 |
| Kgec Limited | Construction | 2013 |
| KH Real Estate Limited | Real estate | 2025 |
| Khalkedon & Co. Ltd | Construction | 2020 |
| Kika's World Ltd | Information & communication | 2026 |
| Kilomaster Limited | Wholesale & retail | 1995 |
| KIM Synclair Limited | Health & social care | 2015 |
| Kimpton Park Developments Ltd | Construction | 2018 |
| KIN Club Retreats Limited | Other services | 2024 |
| Kinder Nutrition Limited | Health & social care | 2019 |
| Kinetic Recruitment Solutions Ltd | Professional & scientific | 2018 |
| Kingdom Education Limited | Education | 1985 |
| Kinloch Court (Management) Limited | Real estate | 2013 |
| Kinsbourne Consultants Limited | Professional & scientific | 2024 |
| Kinsbourne Wealth Management Limited | Financial services | 2019 |
| Kiral Financials Ltd | Professional & scientific | 2016 |
| Kirsti Wenn Consulting Ltd | Administrative & support | 2023 |
| Kitchen Makeovers Ltd | Construction | 2020 |
| KK Enterprises Private Limited | Health & social care | 2025 |
| Klearwater Limited | Professional & scientific | 2021 |
| Knetminer Limited | Professional & scientific | 2023 |
| Knight Infinity Limited | Information & communication | 2020 |
| Knight Infinity Property Ltd | Real estate | 2021 |
| Knights Court (Baldock) Management Company Limited | Real estate | 2008 |
| Knightstone Real Estate Limited | Professional & scientific | 2014 |
| Kobex Solutions Ltd | Professional & scientific | 2012 |
| Kochler UK Ltd | Wholesale & retail | 2021 |
| Kohler Investment Group Ltd | Other services | 2019 |
| Kongtech Limited | Information & communication | 2013 |
| Korner Construction Limited | Construction | 2020 |
| Korner Portfolios Limited | Real estate | 2024 |
| Krbl Ltd | Real estate | 2021 |
| Kreado Malvern Road Ltd | Real estate | 2022 |
| Kriti Limited | Real estate | 2017 |
| Krystal's Nails Ltd | Other services | 2025 |
| Kudos Realty Limited | Real estate | 2023 |
| Kung PO Media Ltd | Information & communication | 2023 |
| Kytes Consultancy Ltd | Education | 2022 |
| L Goodchild Flooring Limited | Construction | 2015 |
| L Johnson Properties Limited | Real estate | 2022 |
| L'Arbre Cleaning Services Ltd. | Other services | 2010 |
| L2DER Ltd | Real estate | 2025 |
| L7 Consulting Ltd | Professional & scientific | 2023 |
| LA Belle Nails & Beauty Ltd | Other services | 2026 |
| LA Rusk Limited | Arts & recreation | 2018 |
| LA Unique Ltd | Health & social care | 2011 |
| Labelle Jade Limited | Other services | 2018 |
| Lambda Photometrics Limited | Manufacturing | 1977 |
| Landart Builders Limited | Construction | 2007 |
| Landart Property Ltd | Real estate | 2018 |
| Lander Consultancy Limited | Information & communication | 2022 |
| Landmark Media Limited | Professional & scientific | 2017 |
| Laplace Ltd | Information & communication | 2017 |
| LAT Redbourn Limited | Construction | 2020 |
| Latitude Marketing Limited | Transport & logistics | 2004 |
| Lavin Cafe Ltd | Hospitality | 2021 |
| Lawes Agricultural Trust | Agriculture & fishing | 2014 |
| Lbca Holdings Limited | Professional & scientific | 2013 |