| JAH Property Management Limited | Households | 2026 |
| JAK Catering Limited | Professional & scientific | 2022 |
| JAK Domestic Services Limited | Administrative & support | 2023 |
| JAK Recruitment Ltd | Administrative & support | 2018 |
| Jakob Property Ltd | Real estate | 2021 |
| JAL Electrical Solutions Ltd | Construction | 2022 |
| Jamarah Associates Ltd | Health & social care | 2019 |
| James Albert Properties Ltd | Real estate | 2021 |
| James Andrew Prams & Nurseries Ltd | Wholesale & retail | 2013 |
| James Bond Limited | Extraterritorial | 2012 |
| James Carpets Design Floors Ltd | Wholesale & retail | 2012 |
| James Price Bespoke Glazing Ltd | Construction | 2022 |
| James Smith & SON (Music Sellers) Limited | Wholesale & retail | 1956 |
| James Thomas Estates Ltd | Real estate | 2020 |
| James Thomason Joinery Ltd | Construction | 2010 |
| Janakesari Enterprises Limited | Wholesale & retail | 2018 |
| Jane B Straw Ltd | Professional & scientific | 2020 |
| Janes Meadow (12 Flats) Management Company Limited | Real estate | 1994 |
| Janes Meadow (6 Flats) Management Company Limited | Households | 1994 |
| Janes Meadow (8 Flats) Management Company Limited | Households | 1994 |
| Janey Care Limited | Education | 2025 |
| Jango’S Ltd | Hospitality | 2023 |
| Janric Limited | Information & communication | 2021 |
| Jarek Works Ltd | Construction | 2026 |
| Jaroplus Ltd | Wholesale & retail | 2025 |
| Jarrowbridge Limited | Real estate | 1978 |
| JAS Electrical Solutions Ltd | Construction | 2021 |
| Jason Greasley Lead Generation Services Limited | Professional & scientific | 2020 |
| Jason Stannard Joinery & Building Ltd | Manufacturing | 2022 |
| Javanah Travel Limited | Administrative & support | 2016 |
| Jawoffshore & Renewables Ltd | Professional & scientific | 2026 |
| Jaymasterz Limited | Health & social care | 2023 |
| Jaymax 46 Logistics Ltd | Transport & logistics | 2013 |
| Jaymc Transport Ltd | Transport & logistics | 2015 |
| Jazzpotato Productions Ltd | Information & communication | 2019 |
| JB AML Services Ltd | Professional & scientific | 2022 |
| JB Bxng Gym Ltd | Arts & recreation | 2021 |
| JB Free Wings Ltd | Other services | 2018 |
| JB Jones Properties Limited | Real estate | 2015 |
| JB Therapy Management Consultant Ltd | Other services | 2013 |
| JBE Construction Ltd | Construction | 2025 |
| JBS Home Improvements Ltd | Construction | 2021 |
| JCH Construction Ltd | Construction | 2023 |
| Jclh Electrical Ltd | Construction | 2026 |
| JCP Valeting and Detailing Ltd | Other services | 2022 |
| JCR Hair Design Ltd | Other services | 2016 |
| JCV Solutions Ltd | Professional & scientific | 2005 |
| JDHPROPERTIES2026 Ltd | Households | 2025 |
| JDM Cabling Solutions Limited | Administrative & support | 2016 |
| JDS Digital Ltd | Professional & scientific | 2022 |
| JDS Training & Therapies Ltd | Education | 2019 |
| JDU Inspection Services Limited | Professional & scientific | 2019 |
| Jebbtrading Limited | Wholesale & retail | 2025 |
| Jedamin UK Limited | Health & social care | 2015 |
| Jeedols Relocations Ltd | Financial services | 2020 |
| Jeem Engineering Services Ltd | Professional & scientific | 2021 |
| Jehu Electrical Ltd | Construction | 2019 |
| JEL Renewables Ltd | Construction | 2019 |
| Jeld Limited | Professional & scientific | 2020 |
| Jellperformance Ltd | Manufacturing | 2026 |
| Jenkins Hospitality Ltd | Hospitality | 2022 |
| Jennywren (NW) Ltd | Hospitality | 2024 |
| Jervis Capital Investment Ltd | Financial services | 2026 |
| Jessica AMY Designs Ltd | Professional & scientific | 2025 |
| Jessop Way Ltd | Health & social care | 2016 |
| JET SET Willy Ltd | Information & communication | 2014 |
| JET Storage Limited | Transport & logistics | 2026 |
| JF Investments Group Ltd | Financial services | 2024 |
| JF Trading Group Ltd | Financial services | 2023 |
| JF21 Investments Ltd | Real estate | 2024 |
| JF22 Investments Ltd | Real estate | 2023 |
| JFR Commercials Ltd | Real estate | 2025 |
| Jfrt Holdings Limited | Financial services | 2018 |
| JGH Developments Limited | Real estate | 2016 |
| Jhcr Property Management Limited | Professional & scientific | 2025 |
| Jhtg Property Limited | Real estate | 2017 |
| Jigsaw Planning and Programme Limited | Professional & scientific | 2021 |
| Jipende Ltd | Other services | 2020 |
| Jish and ROY Foods Ltd | Hospitality | 2024 |
| JJ Care Services Limited | Health & social care | 2016 |
| JJ2 Ltd | Professional & scientific | 2017 |
| Jjmechanical Services Ltd | Construction | 2023 |
| JK Event Crew Hire Limited | Administrative & support | 2017 |
| JL Building & Construction Services Limited | Professional & scientific | 2025 |
| JL Landscaping Services Ltd | Administrative & support | 2025 |
| JLB Aesthetics Limited | Health & social care | 2019 |
| JLB Investments Ltd | Real estate | 2025 |
| JLC Heating and Plumbing Specialists Limited | Construction | 2023 |
| JLC Install Ltd | Construction | 2022 |
| JLJ Transport & Logistics Ltd | Transport & logistics | 2026 |
| JLR Building Maintenance Limited | Construction | 2019 |
| JM Design Engineering Limited | Professional & scientific | 2009 |
| JM Healthcare Ltd | Professional & scientific | 2025 |
| JMB Roofing & Cladding Limited | Construction | 2007 |
| JMC Quality Services Limited | Construction | 2026 |
| Jmech Solutions Ltd | Professional & scientific | 2019 |
| JMI Southport Ltd | Manufacturing | 2018 |
| Jmia Property Ltd | Real estate | 2019 |
| JMK Surveying Ltd | Professional & scientific | 2025 |
| JMW Consultants Limited | Extraterritorial | 2006 |