| JDC Thermography Ltd | Information & communication | 2026 |
| JDM IT Consulting Ltd | Information & communication | 2016 |
| Jduk Outdoor Living Limited | Professional & scientific | 2022 |
| Jeevika International Limited | Wholesale & retail | 2000 |
| Jefferson Associates Ltd | Transport & logistics | 2021 |
| JEM Grips Limited | Information & communication | 2013 |
| JEN Donnelly Garden Supplies Ltd | Wholesale & retail | 2023 |
| Jentf Consulting Ltd | Professional & scientific | 2018 |
| Jerlou Investments Ltd | Real estate | 2023 |
| Jerome Smith Visuals Limited | Professional & scientific | 2018 |
| Jessup Health LLP | | 2023 |
| Jessup Health UK Limited | Health & social care | 1995 |
| JGN Project Management Limited | Information & communication | 2017 |
| Jibson Consulting Ltd | Professional & scientific | 2016 |
| JIT Sangha and Sons Ltd | Real estate | 2019 |
| JJ Mortgages Limited | Financial services | 2020 |
| JJP4 Consulting Limited | Financial services | 2025 |
| Jlc-Virtues Ltd | Administrative & support | 2021 |
| JLS Scenery Ltd | Construction | 2021 |
| JMA Business Consulting Limited | Professional & scientific | 2025 |
| JMD Living Ltd | Real estate | 2026 |
| JML Best Services Limited | Construction | 2025 |
| JMY HR Consulting Ltd | Professional & scientific | 2022 |
| JN Property Rentals Limited | Real estate | 2025 |
| Jnzsa Limited | Wholesale & retail | 2015 |
| Joan & Lalitha Ltd | Arts & recreation | 2019 |
| Jogi Limited | Health & social care | 2023 |
| Johal Brothers Limited | Real estate | 2006 |
| Johal Property Services Limited | Real estate | 2022 |
| Johl Property Ltd | Real estate | 2015 |
| John Stratton Ltd | Professional & scientific | 2014 |
| Jor-Arjun Capital Ltd | Real estate | 2024 |
| Jordan Medical Limited | Health & social care | 2012 |
| Jorgedec Limited | Construction | 2018 |
| Joseph Gabriel Properties Limited | Real estate | 2003 |
| Josephine Avenue Management Company Limited | Households | 2010 |
| Jparroyo Ltd | Wholesale & retail | 2022 |
| JPD Contracting Limited | Information & communication | 2013 |
| JR Lighting Limited | Other services | 2014 |
| JS Digital Consultancy Limited | Information & communication | 2018 |
| JS Legacy Limited | Construction | 2017 |
| JSJ Management Services Ltd | Administrative & support | 2024 |
| JT Business Management Ltd | Education | 2025 |
| JT Investment Management Ltd | Real estate | 2024 |
| JTD Advisory Ltd | Professional & scientific | 2024 |
| Jude Designs Limited | Other services | 2013 |
| Julian Watson Agency Limited | Administrative & support | 2002 |
| Julie Screech Limited | Professional & scientific | 2014 |
| Junkbond Limited | Information & communication | 1992 |
| Jutla Developments Limited | Construction | 2003 |
| Juttla Designs Limited | Information & communication | 2017 |
| Juul Investments Ltd | Real estate | 2011 |
| JW Real Estate Limited | Real estate | 2023 |
| Jwwb Ltd | Administrative & support | 2022 |
| Jykura Property Investments Limited | Real estate | 2017 |
| K & AI Ltd | Real estate | 2023 |
| K & B Studios Ltd | Wholesale & retail | 2001 |
| K & H Design Limited | Professional & scientific | 2015 |
| K & US London Limited | Professional & scientific | 2018 |
| K AUS Books Limited | Professional & scientific | 2010 |
| K Dicks Productions Limited | Professional & scientific | 2023 |
| K Mccorry Consulting Ltd | Professional & scientific | 2011 |
| K&J Property Enterprises Limited | Construction | 2026 |
| K1 Construction Group Ltd | Construction | 2024 |
| K1 Spaces Ltd | Construction | 2025 |
| K3 Crescent Limited | Real estate | 2020 |
| K3 Green Lane Limited | Real estate | 2025 |
| K3 Homes Limited | Real estate | 2019 |
| K4 Homes Limited | Real estate | 2020 |
| Kaaranii Business Solutions Limited | Information & communication | 2008 |
| Kaaranii Properties Limited | Real estate | 2019 |
| Kaikoura Real Estate Ltd | Real estate | 2019 |
| Kailey PM & Consultancy Services Ltd | Information & communication | 2023 |
| Kama IP Limited | Administrative & support | 2018 |
| Karak Chaii Gerrards Cross Ltd | Hospitality | 2023 |
| Karan Singh Ltd | Real estate | 2024 |
| Karen Aujla Notary Public Limited | Professional & scientific | 2023 |
| Karin Timothy HOC Limited | Other services | 2016 |
| Karmal Offworld Limited | Financial services | 2022 |
| Karmic Productions Limited | Information & communication | 2015 |
| Kasuku Ltd | Real estate | 2021 |
| Kate Duncan Limited | Professional & scientific | 2018 |
| Kaur Maths Ltd | Education | 2015 |
| Kaystone Limited | Construction | 1996 |
| KBN Civils Ltd | Construction | 2013 |
| KC Renovations Limited | Construction | 2020 |
| Keenbase Limited | Construction | 1976 |
| Keeping Tabs Ltd. | Professional & scientific | 2002 |
| Keerat Real Estate Limited | Real estate | 2020 |
| Kelly and Kelly Ltd | Professional & scientific | 2024 |
| Kelvedon Investments Ltd | Financial services | 2010 |
| Kemsley Property Management Limited | Real estate | 2024 |
| Kennedy Consultation & Psychological Therapy Ltd | Health & social care | 2017 |
| Kennicott Consultants Limited | Professional & scientific | 2012 |
| Kent Domestic Appliances Limited | Wholesale & retail | 2013 |
| Kent Swiss Ltd | Financial services | 2016 |
| Kentchurch Sandpiper Limited | Professional & scientific | 2023 |
| Keren Investments Limited | Real estate | 2021 |
| KGB Accounting Ltd | Professional & scientific | 2017 |
| KH Pet Care Services Limited | Extraterritorial | 2024 |