| KC Court Reporting Ltd | Administrative & support | 2023 |
| KCT Capital Ltd | Financial services | 2025 |
| KCT Care Ltd | Health & social care | 2026 |
| KDG Landlords Ltd | Real estate | 2017 |
| KDG Legal Ltd | Administrative & support | 2017 |
| KDG Legal Services Ltd | Administrative & support | 2017 |
| KDT2 Limited | Real estate | 2024 |
| Kellino Collective Limited | Real estate | 2025 |
| Kelly Brothers Services Limited | Construction | 2024 |
| Kelly Electrics, Female Electricians Ltd | Construction | 2013 |
| Kelsen Health Care Limited | Health & social care | 2014 |
| Kemm Financials Ltd | Professional & scientific | 2018 |
| Kenitos Piri Piri Wallington Ltd | Hospitality | 2025 |
| Kensford Ltd | Wholesale & retail | 2025 |
| Kentucky Energy Limited | Energy | 2019 |
| Keri Properties Limited | Real estate | 2017 |
| Keri TEK Limited | Professional & scientific | 2018 |
| Kevz Catering Ltd | Hospitality | 2021 |
| Key IT Limited | Information & communication | 2018 |
| Key Realtors Limited | Real estate | 2018 |
| Keycommerce Limited | Wholesale & retail | 2025 |
| Keydrive Motor Services Limited | Administrative & support | 2009 |
| KH Financial Limited | Professional & scientific | 2023 |
| Khaliq Arif Ltd | Information & communication | 2021 |
| Khawaja's&Co Ltd | Information & communication | 2025 |
| Khayam Consultancy Ltd | Professional & scientific | 2020 |
| Kiara Decorating Contractors Limited | Construction | 2002 |
| Kid-Bay Ltd | Wholesale & retail | 2009 |
| Kidbrooke Village Trust CIC | Education | 2024 |
| Kidcare International | Extraterritorial | 2006 |
| Kidwizz Ltd | Information & communication | 2019 |
| Kidz 9 to 5 Ltd | Education | 2010 |
| Kigili Food Limited | Hospitality | 2018 |
| Killenworth Limited | Real estate | 2026 |
| Kilonova Ltd | Arts & recreation | 2017 |
| KIM Barrance Ltd | Transport & logistics | 2017 |
| KIN2 Services Limited | Information & communication | 2023 |
| Kindfame Limited | Information & communication | 2001 |
| King Concrete Pumping Ltd | Construction | 2023 |
| Kingfisher Communications UK Ltd | Information & communication | 2021 |
| Kingfisher Telecom Ltd | Information & communication | 2021 |
| Kingley London Limited | Other services | 2011 |
| Kingsmead Lodge Freehold Limited | Households | 2006 |
| Kingswood Building Services (UK) Limited | Construction | 2008 |
| Kiss Driving School Ltd | Education | 2020 |
| Kith Cars Ltd | Wholesale & retail | 2023 |
| Kitti’S Accountancy and Advisory Ltd | Professional & scientific | 2026 |
| KK Rani Properties Ltd | Real estate | 2021 |
| Kkcj Ltd | Real estate | 2025 |
| KKR Express Limited | Wholesale & retail | 2026 |
| Klein Publishing Ltd | Information & communication | 2014 |
| KLF Structural Design Limited | Professional & scientific | 2018 |
| Klinix Ltd | Health & social care | 2024 |
| KM Property Rental Limited | Other services | 2022 |
| KN Brickwork Ltd | Extraterritorial | 2016 |
| Kngfiresolutions Ltd | Public administration | 2025 |
| Knight Property Rentals Limited | Real estate | 2019 |
| Knight Trustees Limited | Administrative & support | 2023 |
| Knightforce Security Limited | Administrative & support | 2025 |
| Knwz Limited | Hospitality | 2019 |
| KOE Group Ltd | Energy | 2022 |
| Komfortzone Ltd | Construction | 2024 |
| Korea Ltd | Professional & scientific | 2024 |
| Korykos Limited | Extraterritorial | 2013 |
| Koset Project Limited | Construction | 2017 |
| KP Corporation Ltd | Information & communication | 2023 |
| KPL Retail Limited | Wholesale & retail | 2022 |
| KPN Taxwise Ltd | Professional & scientific | 2020 |
| KQ Holding Limited | Financial services | 2020 |
| Kreativity Studio Ltd | Education | 2025 |
| KSK IT Services Ltd | Professional & scientific | 2017 |
| Ksoul Limited | Hospitality | 2022 |
| KT Arts and Entertainments Limited | Arts & recreation | 2025 |
| KT Solicitors Limited | Professional & scientific | 2021 |
| KTA Wellness Lifestyle Solutions Limited | Professional & scientific | 2011 |
| Kudii Limited | Arts & recreation | 2023 |
| Kuklous Healthcare Limited | Health & social care | 2019 |
| Kuklous Healthcare Property Ltd | Real estate | 2025 |
| Kuklous Ltd | Real estate | 2014 |
| Kuria Ltd | Hospitality | 2024 |
| Kvpj Limited | Professional & scientific | 2024 |
| KY International Ltd | Real estate | 2019 |
| L & M Tutors Ltd | Education | 2009 |
| L & R (Carshalton) Ltd | Construction | 2008 |
| L LM Real Estate Limited | Real estate | 2024 |
| L&N Dream Events Ltd | Hospitality | 2024 |
| L&S Builds Ltd | Construction | 2020 |
| L-Cedar Recruitment Ltd | Professional & scientific | 2010 |
| L.Matthews Plumbing & Heating Ltd | Construction | 2023 |
| Laboga Ltd | Wholesale & retail | 2022 |
| Ladchumy Limited | Wholesale & retail | 2019 |
| Lady Lydia Circus Arts Ltd | Arts & recreation | 2022 |
| Lagonda Limited | Professional & scientific | 1970 |
| Lakeside Finance and Accounting Ltd | Professional & scientific | 2025 |
| Laksha Tech Solutions Limited | Information & communication | 2026 |
| Lamb Brothers Ltd | Information & communication | 2023 |
| Landmark Group London Ltd | Construction | 2021 |
| Landmark Paving and Landscaping Limited | Administrative & support | 2020 |
| Lankester Engineering LLP | | 2016 |
| Lark Turner Ltd | Professional & scientific | 2019 |