| Kd&Mcircle Ltd | Arts & recreation | 2020 |
| KDB Scaffolding Ltd | Administrative & support | 2025 |
| KDD Holdings Limited | Financial services | 2025 |
| KDS Electrical Group Ltd | Construction | 2024 |
| KE Accounting Solutions Limited | Professional & scientific | 2025 |
| KE Healthcare Ltd | Health & social care | 2020 |
| Kebra Constructions Ltd | Construction | 2024 |
| Keith Harrison (Milton Keynes) Ltd | Wholesale & retail | 2023 |
| Keith Harrison (Stevenage) Ltd | Wholesale & retail | 2019 |
| KEN Dell Limited | Construction | 2014 |
| Ken.West.Bia Ltd | Health & social care | 2025 |
| Kendal Croft Limited | Professional & scientific | 2017 |
| Kenhurst Fresh and Frozen Foods Limited | Wholesale & retail | 1982 |
| Kensington Health Ltd | Wholesale & retail | 2026 |
| Kent & Surrey Building Contractors Limited | Construction | 2025 |
| Kenwyn Flat Management Company Limited | Households | 1981 |
| Kerene Barefield Ltd | Information & communication | 2013 |
| Kern E-Commerce Ltd | Wholesale & retail | 2026 |
| Kernow GP Design Limited | Professional & scientific | 2017 |
| KES Homes Ltd | Real estate | 2026 |
| Kesnak Healthcare Limited | Health & social care | 2026 |
| Kevann Management Limited | Extraterritorial | 2013 |
| Kevin Carr Consulting Limited | Other services | 2013 |
| Key Electrics Limited | Construction | 2008 |
| Key Service Solutions Ltd | Construction | 2023 |
| Key.Guru Limited | Administrative & support | 2019 |
| Keyp Property Ltd | Real estate | 2017 |
| Keypoint Financial Limited | Financial services | 2012 |
| Keyskillz Ltd | Professional & scientific | 2012 |
| KG Signature Real Estate Limited | Real estate | 2021 |
| Kgac Limited | Hospitality | 2025 |
| KH Construction & Building Limited | Construction | 2021 |
| Khairun Enterprises Limited | Health & social care | 2025 |
| Khalide Trading Limited | Wholesale & retail | 2025 |
| Khaneja Holdings Ltd | Real estate | 2022 |
| KHJ London Ltd | Wholesale & retail | 2025 |
| Khoorana Construction Service Limited | Construction | 2015 |
| Kiera Tudway Limited | Information & communication | 2018 |
| Kiko Aesthetics Ltd | Wholesale & retail | 2015 |
| Kilaijon Ltd | Health & social care | 2020 |
| Kilbourn Consultancy Limited | Professional & scientific | 2025 |
| Kili Contracts Ltd | Professional & scientific | 2022 |
| Kilmanjaro Ltd | Professional & scientific | 2025 |
| Kimko Limited | Wholesale & retail | 2024 |
| Kimmeridge Court (Swindon) Management Company Limited | Households | 2005 |
| Kina Early Years Group Ltd | Education | 2025 |
| Kind Beauty Ltd | Wholesale & retail | 2025 |
| Kindred Tattoo Ltd | Arts & recreation | 2013 |
| Kinetic Capital Holdings Limited | Financial services | 2023 |
| King & Sons Construction Limited | Extraterritorial | 2022 |
| Kingfisher Building and Refurbishments Limited | Construction | 2006 |
| Kingfisher Carpentry Services Ltd | Construction | 2015 |
| Kingfisher Court (Stratford) Management Company Limited | Households | 1988 |
| Kingfisher Court Stratford Limited | Households | 1997 |
| Kingfisher Lure Management Company Limited | Real estate | 1982 |
| Kings Chapel International Church | Other services | 2015 |
| Kingsland Civil Engineering Ltd | Construction | 2025 |
| Kinlochry Services Ltd | Information & communication | 2020 |
| Kirberich Labs Ltd | Information & communication | 2025 |
| Kirberich Ltd | Manufacturing | 2022 |
| Kisanet Limited | Other services | 2018 |
| KIT Jennings Ltd | Information & communication | 2018 |
| Kitchen Ergonomics (Stevenage) Limited | Wholesale & retail | 2019 |
| Kitchen Ergonomics Holdings Limited | Financial services | 2019 |
| Kitchen Ergonomics Limited | Wholesale & retail | 2004 |
| Kite Aviation Services Ltd | Education | 2026 |
| Kite Professional Services Ltd | Information & communication | 2016 |
| Kite Realty Services Ltd | Real estate | 2022 |
| Kite Security Services Ltd | Information & communication | 2021 |
| Kitna Ltd | Extraterritorial | 2012 |
| Kiwi Property Investments Ltd | Health & social care | 2017 |
| KJB Carpentry Limited | Construction | 2017 |
| Kjbeatty IT Services Ltd | Information & communication | 2019 |
| KJS Superstore Ltd | Wholesale & retail | 2018 |
| KJW (Plumbing & Heating) Limited | Construction | 2003 |
| KK Demolition Ltd | Construction | 2019 |
| KK Residentials Ltd | Real estate | 2024 |
| KK3 Services Ltd | Manufacturing | 2025 |
| KKO Developments Limited | Administrative & support | 2025 |
| KKR Advisory Limited | Information & communication | 2025 |
| KL Executive Cars Ltd | Wholesale & retail | 2011 |
| Klaar Design & Marketing Ltd | Professional & scientific | 2025 |
| Klass Community Studios CIC | Information & communication | 2026 |
| Klosek Trans Ltd | Transport & logistics | 2024 |
| KM Estates Limited | Real estate | 2015 |
| KMA Procurement Services Limited | Other services | 2018 |
| KMC Groundworks Limited | Construction | 2015 |
| KMD (UK) Limited | Other services | 2012 |
| KMR RAJ Ltd | Health & social care | 2015 |
| KMS Herts Limited | Other services | 2025 |
| Knebworth Consultancy Service Limited | Health & social care | 1998 |
| Knebworth Kitchens Ltd | Construction | 2021 |
| Knight Official Limited | Other services | 2018 |
| Knightingles Healthcare Limited | Health & social care | 2014 |
| Knightingles Properties Limited | Real estate | 2019 |
| Knights Air Conditioning Ltd | Construction | 2022 |
| Knight’S Place (Baldock) Management Company Limited | Real estate | 2021 |
| Knotwood UK Limited | Wholesale & retail | 2013 |
| Koizi Herts Ltd | Hospitality | 2022 |
| Kokroko Engineering Ltd | Wholesale & retail | 2019 |