| Kier Professional Services Limited | Construction | 2014 |
| Kier Project Investment Limited | Professional & scientific | 1987 |
| Kier Property Developments Limited | Construction | 1966 |
| Kier Property Limited | Construction | 2002 |
| Kier Property Management Company Limited | Households | 2007 |
| Kier Rail Limited | Professional & scientific | 1995 |
| Kier Reading Holdco 1 LLP | | 2014 |
| Kier Reading Holdco 2 LLP | | 2014 |
| Kier Reading LLP | | 2014 |
| Kier Realis Logistics Propco 1 LLP | | 2024 |
| Kier Recycling CIC | Water & waste | 1996 |
| Kier Services Limited | Professional & scientific | 1991 |
| Kier Sharston Limited | Construction | 2025 |
| Kier South Wokingham LLP | | 2024 |
| Kier Southwark Holdco Ltd | Construction | 2025 |
| Kier Stoke Limited | Administrative & support | 2007 |
| Kier Sydenham GP Holdco Limited | Construction | 2013 |
| Kier Sydenham GP Limited | Financial services | 2013 |
| Kier Sydenham Limited | Construction | 2013 |
| Kier Sydenham LP | | 2013 |
| Kier Sydenham Nominee Limited | Extraterritorial | 2013 |
| Kier Trade City Holdco 1 LLP | | 2014 |
| Kier Trade City Holdco 2 LLP | | 2014 |
| Kier Trade City LLP | | 2014 |
| Kier Transportal Limited | Construction | 2013 |
| Kier Transportation Limited | Construction | 2005 |
| Kier Uksc LLP | | 2006 |
| Kier Ventures Limited | Construction | 1979 |
| Kier Ventures Uksc Limited | Extraterritorial | 2007 |
| Kier Warth Limited | Construction | 1987 |
| Kier York Street LLP | | 2016 |
| KIK Ealing Holdings Limited | Real estate | 2025 |
| Kikan Ltd | Hospitality | 2026 |
| KIKI001 Ltd | Extraterritorial | 2018 |
| Kikkie Creative House Ltd | Hospitality | 2026 |
| Kilburn Solutions Ltd | Extraterritorial | 2021 |
| Kilor Accountants Ltd | Professional & scientific | 2021 |
| KIM Property Investments Limited | Financial services | 2018 |
| Kimberley Assets Limited | Real estate | 2025 |
| Kimberley Group Ltd | Real estate | 2024 |
| Kimberley ST Estates Ltd | Real estate | 2023 |
| Kimtech Services Ltd | Wholesale & retail | 2023 |
| Kin's Logistics Ltd | Wholesale & retail | 2021 |
| Kincg Limited | Households | 2018 |
| Kind Call Ltd | Information & communication | 2020 |
| Kindercare Nursery Ltd | Education | 2025 |
| Kinetic Technical Limited | Administrative & support | 2008 |
| King David's Merchants Ltd | Wholesale & retail | 2025 |
| King of Sunshine Productions Ltd | Information & communication | 2019 |
| King Solomon School (UK) Ltd | Education | 2020 |
| King Street Planning Ltd | Professional & scientific | 2022 |
| Kingdom Voice Limited | Other services | 2011 |
| Kingfisher Abodes Limited | Real estate | 2019 |
| Kings Greental Investments Ltd | Real estate | 2022 |
| Kingsburn Properties Limited | Real estate | 1997 |
| Kingsley Care & Consultant Limited | Other services | 2025 |
| Kingsmeade Management Company Limited | Households | 2004 |
| Kingspark Estates Ltd | Real estate | 2018 |
| Kingston Management Salford Ltd | Real estate | 2018 |
| Kingston Securities (UK) Limited | Extraterritorial | 2001 |
| Kingsway Cultivated Ltd | Wholesale & retail | 2018 |
| Kingswood Property Group Limited | Real estate | 2018 |
| Kinncrest Estates Limited | Real estate | 2026 |
| Kinshood Ltd | Professional & scientific | 2016 |
| Kintec Group Limited | Professional & scientific | 2008 |
| Kintec Recruitment Limited | Administrative & support | 2001 |
| Kirk Assets (2) Limited | Extraterritorial | 2015 |
| Kirk Assets Limited | Extraterritorial | 2015 |
| Kirkham's Safety and Training Ltd | Construction | 2016 |
| Kirkhaven Limited | Extraterritorial | 1995 |
| Kirkhill Securities Limited | Real estate | 2024 |
| Kirya Estate Limited | Real estate | 2013 |
| Kitclimb Limited | Real estate | 1987 |
| Kitov Limited | Other services | 2010 |
| Kivrei Tzadikim Ltd | Other services | 2020 |
| Kiwi Prop Limited | Real estate | 2018 |
| Kizomba&Semba Manchester Ltd | Education | 2026 |
| KJ Estates Global Ltd | Real estate | 2025 |
| Kjal Limited | Manufacturing | 2018 |
| KK Distributions Ltd | Wholesale & retail | 2026 |
| KL Invesments Ltd | Real estate | 2025 |
| Klarnow Limited | Information & communication | 2025 |
| Klaxon Talent Ltd | Administrative & support | 2026 |
| KLE Distribution Ltd | Wholesale & retail | 2023 |
| Kleannex Cleaning Company Ltd | Administrative & support | 2024 |
| Kleeq Logistics Limited | Transport & logistics | 2026 |
| Klein Assets Limited | Real estate | 2024 |
| Klemsified UK Limited | Health & social care | 2023 |
| Klirot Ltd | Real estate | 2022 |
| Kloiz Housing Ltd | Real estate | 2025 |
| Kloiz Property Limited | Real estate | 2023 |
| Klyne Design Ltd | Professional & scientific | 2017 |
| KM Sustainable Development Limited | Real estate | 2020 |
| KM Tyre and Tracking Ltd | Wholesale & retail | 2025 |
| KML (MCR) Limited | Administrative & support | 2016 |
| KNA Partnership Limited | Professional & scientific | 2016 |
| KNC Ventures Ltd | Real estate | 2013 |
| Knektu Limited | Information & communication | 2020 |
| Knight Bowie Limited | Professional & scientific | 2023 |
| Knight Homes North West Limited | Real estate | 2025 |