| Jowan Ltd | Health & social care | 2022 |
| Joyce Stone Ltd | Information & communication | 2021 |
| Joyful AHH Limited | Wholesale & retail | 2025 |
| Joyful Clean Solutions Limited | Administrative & support | 2025 |
| Joyful Healthcare Ltd | Health & social care | 2020 |
| Joyful Partnership Ltd | Information & communication | 2024 |
| Joyous Healthcare(Uk) Ltd | Administrative & support | 2017 |
| JP Euro Retail Ltd | Wholesale & retail | 2021 |
| Jpak Ltd | Health & social care | 2011 |
| JPB Labour (UK) Ltd | Professional & scientific | 2022 |
| JPG Safety Limited | Professional & scientific | 2026 |
| JPH Recruitment Limited | Administrative & support | 2009 |
| JPL Contracting Limited | Administrative & support | 2009 |
| JPL Cross Property Ltd | Real estate | 2024 |
| JPM Heating and Plumbing Limited | Construction | 2017 |
| Jpmd Investments Ltd | Real estate | 2025 |
| JQB Ltd | Construction | 2006 |
| JR Chauffeurs Ltd | Transport & logistics | 2020 |
| JR Partners Limited | Real estate | 2025 |
| JR Roofing & Building Limited | Construction | 2025 |
| JR Roofing & Contractors Ltd | Construction | 2019 |
| JR Security Limited | Administrative & support | 2024 |
| JR Storage Solutions Ltd | Transport & logistics | 2026 |
| JRB Cardio Ltd | Health & social care | 2019 |
| JRB Estates Ltd | Real estate | 2018 |
| JRS Building Services and Compliance Management Ltd | Administrative & support | 2015 |
| Jrss Properties Limited | Real estate | 2022 |
| JS EC Property Ltd | Real estate | 2025 |
| JS Facilities Limited | Administrative & support | 2025 |
| JS Resin Limited | Construction | 2021 |
| JS Silver Lining Limited | Health & social care | 2016 |
| JSB Security Ltd | Administrative & support | 2025 |
| JSC Corporation Limited | Financial services | 2024 |
| JSC Interiors Ltd | Construction | 2016 |
| JSC Properties (Kent) Ltd | Real estate | 2024 |
| JSD Afro-Caribbean Superstore Ltd | Wholesale & retail | 2025 |
| JSD Smith Ltd | Construction | 2022 |
| Jsgw Limited | Construction | 2024 |
| Jskke Limited | Construction | 2023 |
| JSM Diagnostics Ltd | Professional & scientific | 2022 |
| JSP Consortium Ltd | Professional & scientific | 2007 |
| Jsstw Limited | Construction | 2024 |
| Jsur Limited | Construction | 2025 |
| JSW Construction Limited | Construction | 2024 |
| Jswgw Limited | Construction | 2025 |
| Jswr Limited | Construction | 2025 |
| Jsyproperty.Investment Ltd | Real estate | 2025 |
| Jsystemz Solutions Ltd | Information & communication | 2011 |
| JT Offshore Ltd | Information & communication | 2025 |
| JTC Group Ltd | Construction | 2021 |
| JTC Products Ltd | Wholesale & retail | 2020 |
| Jtcplumbingservices Ltd | Construction | 2024 |
| Juiced Entertainments Limited | Arts & recreation | 2014 |
| Jukes Child Psychology Ltd | Education | 2024 |
| Julykorbeauty Ltd | Wholesale & retail | 2022 |
| Jumkay Services Limited | Administrative & support | 2024 |
| Junk JAM Education C.I.C. | Education | 2025 |
| Juno Safety Limited | Professional & scientific | 2018 |
| Jush Properties Ltd | Real estate | 2017 |
| Just 1 Site Ltd | Information & communication | 2014 |
| Just Clean Global Services Limited | Administrative & support | 2015 |
| Just Flooring Ltd | Construction | 2024 |
| Just Lets Limited | Real estate | 2001 |
| Just the HEM Ministry | Other services | 2015 |
| JW Surveying Limited | Professional & scientific | 2023 |
| JWC Consultant Limited | Professional & scientific | 2025 |
| JWDEVELOPMENT152 Ltd | Construction | 2025 |
| JWL Services (UK) Limited | Water & waste | 2012 |
| JWM Contracting Ltd | Construction | 2018 |
| JWW Construction Ltd | Construction | 2024 |
| JY Holdings Limited | Real estate | 2017 |
| K & a Cars Sales Limited | Wholesale & retail | 2015 |
| K & M Independent Doctors Limited | Health & social care | 2022 |
| K & T Property Limited | Real estate | 2011 |
| K a Design & Build Limited | Construction | 2013 |
| K C Weddings & Events Ltd | Other services | 2015 |
| K Farrell Building & Roofing Ltd | Construction | 2007 |
| K G ELY Ltd | Construction | 2019 |
| K J & Sons Construction Limited | Construction | 2015 |
| K M Medical Limited | Health & social care | 2010 |
| K Oakes Ltd | Wholesale & retail | 2018 |
| K Scaffolding (South East) Limited | Construction | 2018 |
| K&B Delivery Services Ltd | Transport & logistics | 2018 |
| K&G Medics Limited | Health & social care | 2025 |
| K&L Electrical Services Ltd | Construction | 2023 |
| K&S Maintenance Limited | Administrative & support | 2019 |
| K.F.S Rail Ltd | Construction | 2016 |
| K.I.C.C. Bookstore Limited | Wholesale & retail | 1995 |
| K.K. Plant Hire Limited | Administrative & support | 2009 |
| K.W. Heath (Builders) Limited | Construction | 1973 |
| K2A Cosmetics Limited | Wholesale & retail | 2007 |
| K5 Civil Engineering Ltd | Construction | 2019 |
| K5 Construction Ltd | Construction | 2019 |
| K5 Logistics Limited | Construction | 2009 |
| Kacap Limited | Wholesale & retail | 2024 |
| Kaicom Limited | Administrative & support | 2016 |
| Kaifs Ecommerce Ltd | Wholesale & retail | 2025 |
| Kailon Properties Limited | Households | 2026 |
| Kairon Limited | Education | 2022 |
| Kairos Raison Limited | Wholesale & retail | 2022 |