| JP Domestic Services Limited | Professional & scientific | 2021 |
| JP Wessex Ltd | Wholesale & retail | 2023 |
| JPA Roofing & Leadwork Ltd | Construction | 2020 |
| JPL Consultancy Limited | Extraterritorial | 2021 |
| Jpoc Ltd | Professional & scientific | 2018 |
| JS Office Limited | Professional & scientific | 2015 |
| JS Tree Care Specialists Ltd | Administrative & support | 2025 |
| JSB Capital Ltd | Construction | 2025 |
| JSC Sport Ltd | Wholesale & retail | 2022 |
| JSJ Pound Limited | Real estate | 2020 |
| JSM Accountants and Tax Advisors Limited | Professional & scientific | 2019 |
| JSM ATA Associates Limited | Professional & scientific | 2021 |
| JSM Bestasia Limited | Financial services | 2021 |
| JSM PI Limited | Real estate | 2022 |
| Jsmuk Construction Ltd | Real estate | 2021 |
| Jstat Services Limited | Professional & scientific | 2013 |
| JT Production Services Ltd | Professional & scientific | 2005 |
| JTA Properties Limited | Real estate | 2016 |
| JTR Corporations Limited | Financial services | 2025 |
| Julia King and Associates Ltd | Other services | 2023 |
| Julie Scully Psychotherapy & Supervision Limited | Health & social care | 2024 |
| Junior Adventures Group UK Ltd | Health & social care | 2009 |
| Juniper Consultancy Limited | Administrative & support | 2009 |
| Jupiter Court Flats Limited | Households | 2007 |
| Just Around the Corner (JAC) | Education | 2008 |
| Just ASK Dave Ltd | Construction | 2022 |
| Just Coffees Limited | Hospitality | 2023 |
| Just Does IT Limited | Construction | 2009 |
| Just Dreams Ltd | Professional & scientific | 2022 |
| Just Drop Ltd | Transport & logistics | 2023 |
| Just LNG Limited | Arts & recreation | 2013 |
| Just Muffin Limited | Hospitality | 2023 |
| Just Play Sports (Berkshire) Ltd | Health & social care | 2014 |
| Just Website Designs Ltd | Information & communication | 2011 |
| K Petley Ltd | Professional & scientific | 2019 |
| K&T Prop Limited | Real estate | 2024 |
| K.Amira Limited | Health & social care | 2012 |
| K.B.& Sons Limited | Construction | 1972 |
| K2 Global Limited | Other services | 1999 |
| Kadak and Coffee Limited | Hospitality | 2026 |
| Kaffeebar Ltd | Wholesale & retail | 2022 |
| Kaffka UK Limited | Information & communication | 2003 |
| Kaizen Pest Solutions Limited | Administrative & support | 2024 |
| Kalikose Hair Design Ltd | Other services | 2015 |
| Kamac Holdings Ltd | Financial services | 2011 |
| Kamac Limited | Construction | 2002 |
| Kamax Services Limited | Wholesale & retail | 2014 |
| Kamdom Limited | Health & social care | 2022 |
| Kannan Group of Companies Ltd | Financial services | 2022 |
| Kanreki Limited | Professional & scientific | 2025 |
| Kare Group Limited | Financial services | 2018 |
| Kare Support Services Ltd | Health & social care | 2019 |
| Karehana Consultancy Services Limited | Wholesale & retail | 2018 |
| Karomi Ltd | Information & communication | 2010 |
| Karthar Properties Ltd | Real estate | 2026 |
| KASH4 Ltd | Wholesale & retail | 2021 |
| Kashi Holdings Ltd | Real estate | 2024 |
| Kasri Ltd | Real estate | 2026 |
| Kathryn Sian Dance Ltd | Arts & recreation | 2019 |
| Kathyayani Consultancy Ltd | Information & communication | 2017 |
| Katy Creates Ltd | Professional & scientific | 2018 |
| Kavunira Limited | Health & social care | 2025 |
| Kazoku Kombat Defence Ltd | Education | 2024 |
| KBC Hair Alternatives Limited | Other services | 2023 |
| KBS Electrical and Data Services Holdings Limited | Financial services | 2019 |
| KBS Electrical and Data Services Limited | Construction | 2004 |
| KBS Group Ltd | Financial services | 2026 |
| KC Consulting London Ltd | Administrative & support | 2019 |
| KCC Aerial Fitness Ltd | Arts & recreation | 2023 |
| KCD Developments Ltd | Construction | 2023 |
| KD 3D Ltd | Manufacturing | 2024 |
| KDM Management Services Limited | Information & communication | 2017 |
| Kearsley Consulting Limited | Wholesale & retail | 2019 |
| Kearsley Holdings Limited | Real estate | 2019 |
| Kecachan Limited | Professional & scientific | 2008 |
| Keelin Wright Ltd | Professional & scientific | 2018 |
| Keen Projects Limited | Professional & scientific | 2008 |
| Keep IT Spotless Limited | Administrative & support | 2013 |
| Kegs of Camberley Limited | Wholesale & retail | 2011 |
| Kelly & Co. (Cramb Bros) Limited | Financial services | 1914 |
| Kelly Capital Ltd | Households | 2019 |
| Kemin (U.K.) Limited | Manufacturing | 1974 |
| Kenaya Services Ltd | Transport & logistics | 2018 |
| Kendrick Road Management Company Limited | Households | 2011 |
| Kennedy Invest Limited | Real estate | 2025 |
| Kennedy Roofing and Building Limited | Construction | 2024 |
| Kennel Ride (Properties) Limited | Real estate | 1959 |
| Kennet Court Management Company Limited | Households | 1987 |
| Kenneth PYE Associates Limited | Professional & scientific | 2002 |
| Kenny Atlantic Holdings Limited | Financial services | 2026 |
| Kenny Investment Group Ltd | Real estate | 2016 |
| Kenny Investment SR138 Ltd | Real estate | 2021 |
| Kent Accounting Ltd | Professional & scientific | 2025 |
| Kentish Care Ltd | Health & social care | 2024 |
| Kermedec Solutions Limited | Other services | 2011 |
| Kerr Gardens Management Company Limited | Households | 2012 |
| Kerry Builders GB Limited | Construction | 2006 |
| Kerry Care Limited | Health & social care | 2021 |
| KES Determinations Ltd | Professional & scientific | 2026 |
| Keshava Ltd | Information & communication | 2016 |