| Kettle Boxx Fitness Limited | Arts & recreation | 2015 |
| Keybridge Consultancy Services Ltd | Education | 2026 |
| Keynote Opera Productions Ltd | Information & communication | 2019 |
| Keypoint Projects Ltd | Administrative & support | 2018 |
| KF Challenger XI Limited | Extraterritorial | 2022 |
| KF Challenger XII Limited | Extraterritorial | 2022 |
| KG Recruitment Limited | Administrative & support | 2025 |
| KH D'Satmar Ltd | Other services | 2014 |
| Khamniz Cart Shop Ltd | Wholesale & retail | 2025 |
| Khan Chaai Ltd | Hospitality | 2023 |
| Khan Kabir Holdings Ltd | Financial services | 2026 |
| Khanna and Sons Limited | Health & social care | 2021 |
| Khans Medical Services Ltd | Health & social care | 2020 |
| KHB Group Limited | Real estate | 2024 |
| Kheiltrade Ltd | Wholesale & retail | 2025 |
| Khirland Ltd | Wholesale & retail | 2024 |
| Khodes Recruitment Ltd | Administrative & support | 2025 |
| Khyber Properties Ltd | Real estate | 2022 |
| Kias Trading Limited | Wholesale & retail | 2023 |
| KID From the West Ltd | Wholesale & retail | 2023 |
| Kiddie Corner MCR Ltd | Health & social care | 2026 |
| Kiddie Gardens Ltd | Health & social care | 2025 |
| Kidlington Oxford Investment Co Limited | Real estate | 2026 |
| Kidlington Oxford SPV Limited | Real estate | 2025 |
| Kids Trust | Health & social care | 2010 |
| Kidscan Ltd. | Health & social care | 2001 |
| Kidz Corner Childcare (Holdings) Limited | Administrative & support | 2007 |
| Kidz Corner Childcare Limited | Education | 2011 |
| Kier (Catterick) Limited | Real estate | 2010 |
| Kier (Kent) PSP Limited | Extraterritorial | 2008 |
| Kier (Newcastle) Investment Ltd | Financial services | 2016 |
| Kier (Newcastle) Operation Limited | Construction | 2017 |
| Kier (NR) Limited | Construction | 2008 |
| Kier (Southampton) Development Limited | Real estate | 2015 |
| Kier (Southampton) Investment Limited | Financial services | 2015 |
| Kier (Southampton) Operations Limited | Construction | 2017 |
| Kier Asset Partnership Services Limited | Administrative & support | 2009 |
| Kier Benefits Limited | Extraterritorial | 2013 |
| Kier Bishops Stortford Holdings Limited | Financial services | 2018 |
| Kier Bishops Stortford Limited | Construction | 2018 |
| Kier Bracknell Holdco Ltd | Construction | 2025 |
| Kier Bracknell Ltd | Construction | 2025 |
| Kier Build Limited | Construction | 1981 |
| Kier Business Services Limited | Professional & scientific | 1998 |
| Kier CB Limited | Extraterritorial | 1934 |
| Kier Commercial Investments Limited | Construction | 2000 |
| Kier Commercial Uksc Limited | Extraterritorial | 2007 |
| Kier Construction Limited | Construction | 1987 |
| Kier Cornwall Street Holdings 1 LLP | | 2017 |
| Kier Cornwall Street Holdings 2 LLP | | 2017 |
| Kier Cornwall Street LLP | | 2017 |
| Kier Developments Limited | Construction | 2002 |
| Kier Education Investments Limited | Professional & scientific | 2007 |
| Kier Education Services Limited | Professional & scientific | 2005 |
| Kier Ewan Limited | Extraterritorial | 2001 |
| Kier Facilities Services Limited | Administrative & support | 1991 |
| Kier Finance & Treasury Holdings Limited | Financial services | 2006 |
| Kier Finance Limited | Administrative & support | 2006 |
| Kier Fleet Services Limited | Administrative & support | 1987 |
| Kier Foley Street Holdco 1 LLP | | 2015 |
| Kier Foley Street Holdco 2 LLP | | 2015 |
| Kier Foley Street LLP | | 2015 |
| Kier Graham Defence Limited | Construction | 2013 |
| Kier Green Investments Limited | Construction | 2014 |
| Kier Group Pension Trustees Limited | Extraterritorial | 2009 |
| Kier Group PLC | Professional & scientific | 1992 |
| Kier Group Trustees Limited | Extraterritorial | 1992 |
| Kier HGP Holdings 2 Limited | Construction | 2022 |
| Kier HGP Holdings LLP | | 2022 |
| Kier HGP Tunbridge Wells LLP | | 2023 |
| Kier HGP Weybridge LLP | | 2023 |
| Kier Holdings Limited | Professional & scientific | 2006 |
| Kier Infrastructure and Overseas Limited | Construction | 1974 |
| Kier Integrated Services (Estates) Limited | Real estate | 1926 |
| Kier Integrated Services (Holdings) Limited | Financial services | 2001 |
| Kier Integrated Services (Trustees) Limited | Extraterritorial | 1998 |
| Kier Integrated Services Group Limited | Financial services | 1989 |
| Kier Integrated Services Limited | Water & waste | 1966 |
| Kier International (Investments) Limited | Professional & scientific | 1979 |
| Kier International Limited | Construction | 1964 |
| Kier Limited | Professional & scientific | 1982 |
| Kier Logistics (Bognor) Ltd | Construction | 2021 |
| Kier Logistics (Knowsley) Ltd | Construction | 2021 |
| Kier Logistics (Milton Keynes) Ltd | Construction | 2021 |
| Kier Logistics (ST. Albans) Ltd | Construction | 2021 |
| Kier Logistics Holdco Ltd | Construction | 2021 |
| Kier Maidenhead Holdings 1 LLP | | 2020 |
| Kier Maidenhead Holdings 2 LLP | | 2020 |
| Kier Maidenhead LLP | | 2020 |
| Kier Management Consulting Limited | Professional & scientific | 1990 |
| Kier MBS Limited | Real estate | 2018 |
| Kier Midlands Limited | Extraterritorial | 1946 |
| Kier Minerals Limited | Construction | 1987 |
| Kier National Limited | Professional & scientific | 1987 |
| Kier North Tyneside Limited | Administrative & support | 2009 |
| Kier Overseas (Nine) Limited | Construction | 1980 |
| Kier Overseas (Seventeen) Limited | Construction | 1979 |
| Kier Overseas (Twenty-Three) Limited | Construction | 1987 |
| Kier Parkman Ewan Associates Limited | Extraterritorial | 1995 |
| Kier Plant Limited | Construction | 2001 |