| Joy Foods Group Ltd | Manufacturing | 2026 |
| Joy Investments Limited | Extraterritorial | 2015 |
| Joylious Wonder Limited | Wholesale & retail | 2025 |
| Joymox Ltd | Real estate | 2025 |
| JP Accounting Consultancy Ltd | Professional & scientific | 2018 |
| JP Amadores Limited | Real estate | 2025 |
| JP Consultancy London Limited | Administrative & support | 2019 |
| JP Management Services Ltd | Information & communication | 2016 |
| JP05 Ltd | Real estate | 2025 |
| JPB London Ltd | Real estate | 2025 |
| JPD Urology Consultancy UK Ltd | Health & social care | 2019 |
| JPL SNL Ltd | Financial services | 2019 |
| Jpml Housing Limited | Hospitality | 2018 |
| Jpsb Solutions Limited | Information & communication | 2017 |
| JPT Ventilation Limited | Construction | 2019 |
| JRE Building Services Ltd | Construction | 2025 |
| JRG Plumbing & GAS Ltd | Construction | 2024 |
| JRH Assets Limited | Real estate | 2025 |
| JRH Services Ltd | Construction | 2017 |
| Jrsh Group Limited | Wholesale & retail | 2023 |
| JS Financial Services (London) Limited | Financial services | 2009 |
| JS Global Ventures Ltd | Wholesale & retail | 2020 |
| JS Healthcare Consulting Ltd | Professional & scientific | 2025 |
| JSD Solutions 24/7 Ltd | Water & waste | 2016 |
| JSM Talent Ltd | Professional & scientific | 2026 |
| JSM Woodwork Limited | Manufacturing | 2022 |
| JST Investment Limited | Real estate | 2019 |
| JSV Limited | Construction | 2021 |
| JT Developments Plus Ltd | Real estate | 2024 |
| JTS Capital Ltd | Financial services | 2026 |
| Jubilee Holdings Limited | Information & communication | 2021 |
| Judges Dining Restaurant Ltd | Hospitality | 2025 |
| Judges Fine Dining Ltd | Hospitality | 2026 |
| Juicygroove Limited | Information & communication | 1998 |
| Juladore Limited | Wholesale & retail | 2016 |
| Julie House Management Company Limited | Households | 1995 |
| Juliet Court Management Company Limited | Households | 1980 |
| Juliet Most Coaching Limited | Administrative & support | 2019 |
| Julka Investment Limited | Real estate | 2024 |
| Julka Properties Ltd | Real estate | 2020 |
| June Lawrence Limited | Professional & scientific | 2012 |
| Juniper Advisory Ltd | Professional & scientific | 2024 |
| Juniper Heights Management Limited | Households | 1986 |
| Juniper Louise Ltd | Financial services | 2015 |
| Junita Limited | Administrative & support | 1992 |
| Jupiter Estates Limited | Real estate | 2018 |
| Jupiter International Solutions Limited | Administrative & support | 2020 |
| Jupiter Rock Limited | Administrative & support | 2018 |
| Jupiter Visual Communications Limited | Manufacturing | 2014 |
| Jurassic Property Developments Limited | Extraterritorial | 2019 |
| Just Chill Mama Limited | Other services | 2020 |
| Just Facility Management Limited | Administrative & support | 2018 |
| Just FM Facilities Management Group Ltd | Professional & scientific | 2004 |
| Just Like Home Ltd | Education | 2015 |
| Just Mosaic Ltd | Construction | 2008 |
| Just Nominees Limited | Professional & scientific | 1995 |
| Just One Tree C.I.C. | Agriculture & fishing | 2019 |
| Just Reception Ltd | Administrative & support | 2013 |
| Justducks Ltd | Wholesale & retail | 2009 |
| Justines Ltd | Administrative & support | 2025 |
| Jutland Close Management Limited | Households | 1988 |
| JVD Properties LLP | | 2016 |
| JVJ Limited | Real estate | 2021 |
| Jvms Limited | Wholesale & retail | 1997 |
| JWM Care Limited | Health & social care | 2021 |
| JYC Property Group Limited | Real estate | 2025 |
| JZ Consultancy Services Ltd | Information & communication | 2019 |
| K & D Polishing Limited | Other services | 2020 |
| K & J Strachan Ltd | Financial services | 2014 |
| K & K Lettings London Ltd | Real estate | 2015 |
| K & M Companies Limited | Administrative & support | 2019 |
| K Advisory Ltd | Professional & scientific | 2024 |
| K Carvell Builders Limited | Construction | 2017 |
| K D Gardens Ltd | Wholesale & retail | 2025 |
| K F Wanda Ltd | Administrative & support | 2019 |
| K H Home Construction Limited | Construction | 2019 |
| K Jennings Ltd | Other services | 2010 |
| K K Developers Limited | Construction | 2010 |
| K K P R Limited | Wholesale & retail | 1993 |
| K M Musiq Limited | Information & communication | 2007 |
| K Properties 208 Ltd | Real estate | 2026 |
| K Properties 231 Ltd | Real estate | 2026 |
| K&V Holdings Ltd | Households | 2018 |
| K.Cela Construction Limited | Construction | 2022 |
| K.G. Investments Limited | Real estate | 2006 |
| K.G.B. Packaging Limited | Professional & scientific | 2002 |
| K.K. School of Driving Ltd | Education | 2020 |
| K2 Trading International Ltd | Wholesale & retail | 2025 |
| K5 Capital Partners Ltd | Other services | 2022 |
| KA Wellness Ltd | Health & social care | 2026 |
| Kaasa Ltd | Real estate | 2023 |
| Kaizen Supported Housing Ltd | Health & social care | 2020 |
| Kakar Ltd | Real estate | 2024 |
| Kalawana Associates Limited | Real estate | 2026 |
| Kalia Studio Ltd | Wholesale & retail | 2025 |
| Kallisto Homes Management Company Limited | Households | 2022 |
| Kalra Global Consulting Limited | Wholesale & retail | 2019 |
| Kalute Chivela Ltd | Transport & logistics | 2019 |
| KAM International Properties Ltd | Real estate | 2025 |
| Kamb Consulting Limited | Professional & scientific | 2010 |