| Jpas Sales Ltd | Wholesale & retail | 2018 |
| Jplews Consultancy Ltd | Professional & scientific | 2025 |
| JPP Building Contractors Limited | Construction | 2021 |
| JPS Fire Consultancy Ltd | Professional & scientific | 2020 |
| JPS Landscaping Limited | Construction | 2021 |
| JPW Accountancy LLP | | 2019 |
| JR Chuo Ltd | Arts & recreation | 2023 |
| JR Jewellers Ltd | Manufacturing | 2025 |
| JR Performance Motors Ltd | Wholesale & retail | 2025 |
| JR Systems Ltd | Construction | 2024 |
| Jrbuk Trading Limited | Wholesale & retail | 2025 |
| JRE Repairs Ltd | Wholesale & retail | 2026 |
| JRF Developments Ltd | Construction | 2013 |
| JRG Design Engineering Limited | Administrative & support | 2012 |
| JRJ Services Limited | Professional & scientific | 2015 |
| JRJ Winter Ltd | Transport & logistics | 2025 |
| JRK Contract Services Limited | Manufacturing | 2019 |
| Jrohi Limited | Health & social care | 2011 |
| Jrxclusive Ltd | Wholesale & retail | 2025 |
| JS & W Holdings Limited | Professional & scientific | 2024 |
| JS Electrical Services London Ltd | Construction | 2019 |
| JSB Furniture Limited | Wholesale & retail | 2017 |
| JSD Law UK Ltd | Professional & scientific | 2024 |
| JSS Plumbing & Heating Ltd | Construction | 2017 |
| JST Designs Ltd | Manufacturing | 2026 |
| JTL Group Ltd | Construction | 2022 |
| JTM Health Ltd | Public administration | 2021 |
| Juako Fashion Ltd | Wholesale & retail | 2025 |
| Jubilee Farm Suffolk Ltd | Agriculture & fishing | 2023 |
| Juice Club Ltd | Hospitality | 2024 |
| Juicebros Ltd | Hospitality | 2018 |
| Juicified Ltd | Other services | 2024 |
| Juicy LAD Beverages Limited | Wholesale & retail | 2025 |
| Julyseventh Limited | Information & communication | 2025 |
| Jump K.K. Enterprises Limited | Professional & scientific | 2003 |
| Jumpwest Limited | Other services | 2025 |
| Junior to Senior Limited | Public administration | 2021 |
| Juniper International Group Limted UK Ltd | Professional & scientific | 2019 |
| Just BAM Accounts Ltd | Professional & scientific | 2023 |
| Just Beard Things Ltd | Other services | 2024 |
| Just Cool Beans Ltd | Wholesale & retail | 2025 |
| Just Glaze Limited | Construction | 2019 |
| Just Jollof UK Ltd | Manufacturing | 2024 |
| Just MD Limited | Professional & scientific | 2022 |
| Just Right Events Ltd | Information & communication | 2017 |
| Just WIN Sheff C.I.C. | Health & social care | 2024 |
| Justonehome Ltd | Information & communication | 2024 |
| JVB Digital Business Ltd | Wholesale & retail | 2025 |
| JW Creative Carpentry Limited | Construction | 2013 |
| JW Seed Tech Ltd | Agriculture & fishing | 2025 |
| JW Social Work Consultants Ltd | Health & social care | 2015 |
| JWA Projects Ltd | Professional & scientific | 2020 |
| JWB Global Ltd | Wholesale & retail | 2025 |
| JWB Network Ltd | Administrative & support | 2023 |
| Jwcarpentry Building Services Ltd | Construction | 2021 |
| JWG Transit Ltd | Transport & logistics | 2026 |
| Jy&D Consultancy Ltd | Public administration | 2024 |
| JZ Consulting Limited | Financial services | 2018 |
| K & M Cleaning Limited | Administrative & support | 2002 |
| K & N Express Mini Market Ltd | Wholesale & retail | 2025 |
| K and S Solutions Ltd | Health & social care | 2017 |
| K B S Roofing Ltd | Construction | 2002 |
| K D Knight Supplies Ltd | Manufacturing | 2020 |
| K Jeffrey Quality Construction and Refurbishment Ltd | Construction | 2022 |
| K Levell and Sons Limited | Construction | 2024 |
| K Wagstaff & J Morton Limited | Other services | 2017 |
| K&D Property Services Ltd | Real estate | 2025 |
| K&K Real Estate Development Limited | Construction | 2017 |
| K&S Construction Services Ltd | Construction | 2025 |
| K&Z Balloons Ltd | Arts & recreation | 2025 |
| K-Mart Supermarket Limited | Wholesale & retail | 2025 |
| K-Os Visuals Ltd | Information & communication | 2021 |
| K. Ollett Limited | Transport & logistics | 2007 |
| K.Arms Bicester Hotel Limited | Hospitality | 2026 |
| K.Hardy CSM Ltd | Professional & scientific | 2025 |
| K.J. (Holdings) Limited | Construction | 1987 |
| K.J. Lakacauskas Limited | Transport & logistics | 2026 |
| K.Kentchadze Limited | Transport & logistics | 2025 |
| K.Mosejus Ltd | Transport & logistics | 2025 |
| K.Savukynas Ltd | Transport & logistics | 2024 |
| K.Sepov Ltd | Transport & logistics | 2025 |
| K2 Mintrade Ltd | Wholesale & retail | 2023 |
| K28 Limited | Wholesale & retail | 2026 |
| K8CREATES Limited | Professional & scientific | 2022 |
| K9 Defence Ltd | Administrative & support | 2024 |
| K9 Hygiene Solutions Ltd | Administrative & support | 2026 |
| K9 Krew & Friends Pet Services Ltd | Professional & scientific | 2026 |
| KAB Group Ltd | Administrative & support | 2026 |
| Kabley Consulting Ltd | Professional & scientific | 2026 |
| Kachiya Ltd | Wholesale & retail | 2024 |
| KAD Escapes Limited | Hospitality | 2025 |
| Kadd Investments Ltd | Real estate | 2024 |
| Kadd Properties Ltd | Hospitality | 2025 |
| Kader and Partners Ltd | Health & social care | 2021 |
| Kafina Ltd | Wholesale & retail | 2025 |
| KAI Chiu Residential Limited | Real estate | 2024 |
| KAI Events Ltd | Information & communication | 2025 |
| Kaico Group Limited | Wholesale & retail | 2023 |
| Kaicocards Ltd | Wholesale & retail | 2026 |
| Kailaitrade Ltd | Wholesale & retail | 2025 |