| Ivel Precision Laser Cutting Ltd | Manufacturing | 2018 |
| Ivel Property Management Ltd | Households | 2022 |
| Ivel Roofing Ltd | Manufacturing | 2021 |
| Ivjc Ltd | Information & communication | 2025 |
| IVO Digital Limited | Information & communication | 2017 |
| J and J Prime Properties Limited | Real estate | 2026 |
| J B S Developers Limited | Construction | 1995 |
| J Harrison Consultancy Limited | Professional & scientific | 2024 |
| J Nolan Consultancy Ltd | Administrative & support | 2023 |
| J&H Carpentry Ltd | Manufacturing | 2025 |
| J&K Property Management Services Ltd | Real estate | 2025 |
| J. Flint Electrical Contractors Limited | Construction | 1984 |
| J. Flint Services Limited | Extraterritorial | 2011 |
| J.K. Engineering Services Limited | Other services | 2000 |
| Jack Bygraves Ltd | Wholesale & retail | 2020 |
| Jackson Christie Limited | Construction | 2019 |
| Jacqui Fletcher Limited | Health & social care | 2016 |
| JAE Rail Ltd | Professional & scientific | 2022 |
| James Bowman & Sons Limited | Extraterritorial | 1999 |
| James Menzies Limited | Arts & recreation | 2018 |
| James Newbury Appointments Limited | Administrative & support | 2015 |
| Jamie Clarkson Ltd | Manufacturing | 2016 |
| Janush Food & Wine Ltd | Wholesale & retail | 2013 |
| Jbme Party Co. Ltd | Arts & recreation | 2024 |
| JD Coaching Limited | Other services | 2021 |
| JDH Interiors Limited | Wholesale & retail | 2014 |
| JDW Sign Services Ltd | Construction | 2024 |
| Jeal & Co Roofing Ltd | Wholesale & retail | 2025 |
| Jennie LEE Limited | Education | 2018 |
| Jenolite (UK) Limited | Wholesale & retail | 2013 |
| Jerk Store Productions Ltd | Information & communication | 2016 |
| Jetpen Limited | Information & communication | 2023 |
| Jewell Enterprises Limited | Professional & scientific | 2017 |
| Jewers Doors Holdings Limited | Financial services | 2026 |
| Jewers Doors Limited | Manufacturing | 1984 |
| Jhmm Solutions Ltd | Construction | 2025 |
| Jholby Protection Ltd | Financial services | 2023 |
| JLS Building and Property Development Ltd | Construction | 2025 |
| Jltv Digital Ltd | Professional & scientific | 2025 |
| Jltv Digital Productions Ltd | Information & communication | 2025 |
| JM Nails & Beauty Ltd | Other services | 2016 |
| JM Property Group Limited | Construction | 2014 |
| JNL Rail Ltd | Transport & logistics | 2026 |
| JNN (Jast-Safe Home Care) Ltd | Health & social care | 2015 |
| JNW Hsqe & Compliance Ltd | Professional & scientific | 2024 |
| Jo's Pantry Limited | Manufacturing | 2020 |
| Johann Ackerman Limited | Health & social care | 2008 |
| John Shepherd (Motors) Limited | Wholesale & retail | 1984 |
| Jones Assist UK Ltd | Construction | 2020 |
| Jones' Physio & Wellness Clinic Limited | Other services | 2024 |
| Jordan Cine Limited | Information & communication | 2023 |
| Jordans Mill Trading Limited | Wholesale & retail | 2021 |
| Joseph Jacobs Ltd | Professional & scientific | 2015 |
| Jo’S Ices Ltd | Wholesale & retail | 2022 |
| JRS Accountancy Limited | Professional & scientific | 2010 |
| Jtsl Festive Lighting Ltd | Construction | 2025 |
| Jtsl Ltd | Wholesale & retail | 2023 |
| Junction Collective Ltd | Administrative & support | 2023 |
| Junder Co Ltd | Information & communication | 2016 |
| Just Being ME Events Collective CIC | Health & social care | 2026 |
| Just Recruit Software Limited | Information & communication | 2018 |
| Justin Evans Ltd | Information & communication | 2009 |
| JWJ Holdings Ltd | Financial services | 2021 |
| K&D Escapes Ltd | Administrative & support | 2023 |
| K. & H. Thermal Insulations Limited | Construction | 1973 |
| K.O. Specialist Limited | Professional & scientific | 2014 |
| Kalisi Developments Limited | Construction | 2018 |
| Karawak Limited | Information & communication | 1992 |
| Karder Properties Limited | Real estate | 2024 |
| KBD Properties Ltd | Real estate | 2026 |
| Kbme Limited | Extraterritorial | 2017 |
| KBO Acquisitions Ltd | Real estate | 2014 |
| KCR Property Ltd | Real estate | 2019 |
| KDS Site Investigations Ltd | Professional & scientific | 2013 |
| KEB Property Investments Ltd | Real estate | 2021 |
| Keepbeep Ltd | Information & communication | 2021 |
| Keeves & SON Ltd | Wholesale & retail | 2014 |
| Keiki Talent Ltd | Administrative & support | 2026 |
| Kennet Aviation Ltd | Professional & scientific | 2018 |
| Keyo Estates Ltd | Other services | 2016 |
| Khyne Limited | Professional & scientific | 2016 |
| Khyne Properties Limited | Real estate | 2026 |
| Kick Back Consulting Ltd | Professional & scientific | 2024 |
| Kingfisher Garden & Pond Solutions Ltd | Administrative & support | 2021 |
| Kitchenalia Limited | Wholesale & retail | 2004 |
| Kitchworks Ltd | Construction | 2024 |
| Kitten Poker Creations Ltd | Arts & recreation | 2025 |
| Kitten Poker Ltd | Professional & scientific | 2002 |
| Kiyos Ltd | Construction | 2022 |
| Kkba Properties Ltd | Real estate | 2025 |
| KKD Healthcare and Recruitment Limited | Administrative & support | 2022 |
| Kklc Furniture Ltd | Wholesale & retail | 2025 |
| Knightingles Healthcare (Bedfordshire) Ltd | Health & social care | 2017 |
| Komorebi Health Ltd | Wholesale & retail | 2024 |
| Komorebi Therapies Ltd | Health & social care | 2019 |
| Kompozit'All UK Limited | Construction | 2010 |
| Koncept Castles LLP | | 2023 |
| Koncept Productions Ltd | Arts & recreation | 2019 |
| Konect Global Solutions Ltd | Administrative & support | 2023 |
| Kp&Sons Properties Biggleswade Ltd | Real estate | 2022 |