| King George Court (Chelmsford) Management Company Limited | Households | 2005 |
| King Good Solutions Ltd | Manufacturing | 2025 |
| King Safety and Security Ltd | Administrative & support | 2014 |
| Kingfield Consulting Ltd | Professional & scientific | 2016 |
| Kingfisher Project Solutions Ltd | Professional & scientific | 2025 |
| Kingfisher Trading Company Limited | Real estate | 1985 |
| Kingley Grange Management Limited | Households | 2013 |
| Kings Drive Management Company Limited | Households | 2026 |
| Kingsfleet Park (Trimley ST. Martin) Management Company Limited | Households | 2025 |
| Kingsford Holdings Ltd | Real estate | 2021 |
| Kingsman Consultant Limited | Information & communication | 2025 |
| Kingsmead (Stanford-Le-Hope) Management Limited | Households | 1991 |
| Kingsmere Partners LLP | | 2025 |
| Kingston Gardens Management Company Limited | Households | 2002 |
| Kingswood Joinery UK Limited | Manufacturing | 2006 |
| Kingswood Park (Colchester) Management Company Limited | Households | 2006 |
| Kink Tattoo Studios Ltd | Other services | 2021 |
| Kinvara Group Limited | Financial services | 2022 |
| Kinzo Limited | Hospitality | 2020 |
| Kira (UK) Ltd | Manufacturing | 2009 |
| Kirbha Limited | Health & social care | 2017 |
| Kirch Technology Solutions Ltd | Professional & scientific | 2024 |
| Kirkby Homes Developments Limited | Construction | 2017 |
| Kirkfield Supplies Ltd | Manufacturing | 2013 |
| Kirkham Florists Limited | Wholesale & retail | 2019 |
| Kirsty's Dance Academy Limited | Education | 2021 |
| Kirtana Consulting UK Limited | Information & communication | 2012 |
| Kirtana Healthcare Limited | Health & social care | 2023 |
| Kisby Wholesale Limited | Wholesale & retail | 2025 |
| Kiss & Kiss Ltd | Transport & logistics | 2020 |
| Kiss and Tail Ltd | Professional & scientific | 2023 |
| Kitchens and Pro-Duct Clean Ltd | Administrative & support | 2019 |
| Kiteframe Ltd | Information & communication | 2016 |
| Kittle Group (UK) Ltd | Administrative & support | 2014 |
| Kittle Leavers Limited | Professional & scientific | 2023 |
| Kittle Photographic Limited | Professional & scientific | 2000 |
| Kittle Visual Marketing Limited | Information & communication | 2011 |
| Kiyn Ventures Limited | Real estate | 2026 |
| KJA Rooftech Limited | Professional & scientific | 2019 |
| KJC Investments Limited | Professional & scientific | 2023 |
| KJF Investments Limited | Real estate | 2023 |
| KJS Electrical Contractors Limited | Construction | 2016 |
| KK Garden Studio Limited | Professional & scientific | 2025 |
| Kkalani Consultancy Ltd | Information & communication | 2019 |
| Kkche Property Services Ltd | Real estate | 2023 |
| KKM Media Ltd | Administrative & support | 2023 |
| KL Connolly Limited | Information & communication | 2010 |
| KL Construction Supply & Sourcing Ltd | Wholesale & retail | 2025 |
| KLE Design Limited | Professional & scientific | 2014 |
| Klik Limited | Information & communication | 2013 |
| Klmconsultancy Ltd | Real estate | 2019 |
| KLP Services Ltd | Professional & scientific | 2016 |
| KLS Driver Training Limited | Education | 2024 |
| KM Home Garden Maintenance Limited | Other services | 2025 |
| Kmac Investments Ltd | Real estate | 2019 |
| Kmary Venture Limited | Administrative & support | 2014 |
| Kmcs Group Limited | Administrative & support | 2017 |
| Kmimports Ltd | Wholesale & retail | 2026 |
| Kmkr Ltd | Real estate | 2018 |
| KMP Services & Solutions Ltd | Information & communication | 2019 |
| KMP UK Tactical Ltd | Other services | 2020 |
| KMS Training Ltd | Education | 2013 |
| KMT Brickwork Limited | Construction | 2021 |
| Kmtn Ltd | Administrative & support | 2026 |
| KN Elite Group Limited | Financial services | 2020 |
| KN Elite Limited | Professional & scientific | 2020 |
| Knappr Limited | Wholesale & retail | 2021 |
| Knight Design (Interiors) Limited | Professional & scientific | 2000 |
| Knights Accountancy Solutions Limited | Professional & scientific | 2016 |
| Knights Consultancy Limited | Wholesale & retail | 2025 |
| Knights Reckoning Limited | Information & communication | 2023 |
| Knights Safety Services Limited | Professional & scientific | 2026 |
| Knights Since 1759 Ltd | Manufacturing | 2011 |
| Knockout Challenge Limited | Arts & recreation | 2000 |
| Know Escape Franchise Ltd | Arts & recreation | 2019 |
| Know Escape Ltd | Arts & recreation | 2017 |
| Knowall AI Limited | Professional & scientific | 2019 |
| Knowledge Well Group Limited | Education | 2009 |
| Knowledge Well Limited | Education | 2007 |
| Knowntoache Ltd | Professional & scientific | 2025 |
| Koba Kitchens and Bathrooms Ltd | Construction | 2024 |
| Kobinash Property Ltd | Real estate | 2020 |
| Koby Management Limited | Professional & scientific | 2020 |
| Kodah Developments Ltd | Construction | 2024 |
| Kodesa Limited | Construction | 2007 |
| Kofos Catering Services Limited | Hospitality | 2025 |
| KOH Consulting Ltd | Professional & scientific | 2026 |
| Kohlers Estate Agents Limited | Real estate | 2025 |
| Kokakev Ltd | Real estate | 2025 |
| Koko Dairo Fashion and Beauty House Ltd | Manufacturing | 2025 |
| KON & Ching Engineering Limited | Professional & scientific | 2007 |
| Kongstruction Limited | Construction | 2025 |
| Kontact Events Ltd | Administrative & support | 2013 |
| Kosk (UK) Ltd | Hospitality | 2013 |
| Kosmic Consulting Limited | Professional & scientific | 2016 |
| Koumides Property Investments Ltd | Real estate | 2019 |
| Koumides Property Management Ltd | Real estate | 2023 |
| Kova Asbestos Consultants Limited | Professional & scientific | 2014 |
| Kova Asbestos Management Services Limited | Professional & scientific | 2016 |
| Kova Holdings Limited | Financial services | 2019 |