| Irthling Group Ltd. | Wholesale & retail | 2020 |
| Isaac Mulisa Services Ltd | Transport & logistics | 2012 |
| Isabella Court Freehold Limited | Households | 2021 |
| Isaiah's Roofing & Building Ltd | Construction | 2025 |
| Iseemed Ltd | Wholesale & retail | 2014 |
| ISEVENTY9 Repairs Limited | Wholesale & retail | 2020 |
| Isiktan Ltd | Other services | 2025 |
| Isiton Grace Ltd | Health & social care | 2020 |
| Island Avenue Limited | Information & communication | 2014 |
| Island Blue Limited | Wholesale & retail | 2019 |
| Ismart Web Solutions Ltd | Professional & scientific | 2020 |
| Ispas Logistics Limited | Transport & logistics | 2014 |
| Istd Pharmatech Ltd | Administrative & support | 2023 |
| Istrate Building Ltd | Construction | 2022 |
| IT Assets Management Limited | Information & communication | 2015 |
| IT Global Tech Limited | Professional & scientific | 2012 |
| IT Teck Limited | Wholesale & retail | 2011 |
| It.Data Secured Limited | Wholesale & retail | 2022 |
| Italian Touch Limited | Hospitality | 2002 |
| Italindo Ltd | Professional & scientific | 2020 |
| Itarath Limited | Health & social care | 2020 |
| Itelligent Limited | Information & communication | 2010 |
| Ithairworld Ltd | Wholesale & retail | 2026 |
| Itna Ltd | Hospitality | 2025 |
| Itssie Limited | Information & communication | 2014 |
| Iuga Construction Ltd | Construction | 2026 |
| Iulia Online Ltd | Wholesale & retail | 2020 |
| Ivory Grove Wellness and Lifestyle Limited | Health & social care | 2025 |
| Ivory Supported Living Ltd | Health & social care | 2024 |
| IXO Services Ltd | Transport & logistics | 2024 |
| IZA Doughy Delites UK Ltd | Wholesale & retail | 2024 |
| Izzac's Kitchen Ltd | Hospitality | 2020 |
| I’M Sitting Pretty Ltd | Wholesale & retail | 2023 |
| J & a Builders Surplus Limited | Wholesale & retail | 2019 |
| J & a Letting Ltd. | Real estate | 2016 |
| J & C Sheppard Limited | Real estate | 2003 |
| J & G Exterior Cleaning Services Ltd | Administrative & support | 2026 |
| J & J Scaffolding Ltd | Construction | 2024 |
| J & N Roofing and Property Maintenance Ltd | Construction | 2021 |
| J B Irwin Engineering Limited | Construction | 2019 |
| J Berry & Sons Ltd | Construction | 2014 |
| J D Succulents & Cacti Limited | Wholesale & retail | 2018 |
| J Dickins Designs Ltd | Professional & scientific | 2019 |
| J Florence Wholesale Ltd | Wholesale & retail | 2026 |
| J G Technical Operations Ltd | Manufacturing | 2021 |
| J Hickman Traditional Stonewalling and Landscaping Ltd | Administrative & support | 2024 |
| J Hunter & Co Limited | Wholesale & retail | 2016 |
| J HWD Ltd | Construction | 2026 |
| J K Lofts Ltd | Manufacturing | 2022 |
| J Knight Plumbing & Heating Ltd | Construction | 2018 |
| J M R Commercial Properties Ltd | Real estate | 2022 |
| J Middleton Accounting Ltd | Professional & scientific | 2024 |
| J Nash Consulting Limited | Administrative & support | 2024 |
| J R Budino Seafoods Limited | Wholesale & retail | 2018 |
| J&J Medical GAS Ltd | Construction | 2025 |
| J&J Nurseries Limited | Education | 2026 |
| J&K Property Experts Ltd | Real estate | 2025 |
| J&M Tree Care Limited | Administrative & support | 2025 |
| J&T Vertrieb Ltd | Information & communication | 2022 |
| J-1:8 Healthcare Limited | Health & social care | 2021 |
| J-Mec Contracts Ltd | Construction | 2020 |
| J-Shammah Ltd | Health & social care | 2025 |
| J. Curry and Co Limited | Other services | 2015 |
| J.A.W Contracts Limited | Other services | 2017 |
| J.A.W Property Limited | Other services | 2019 |
| J.A.W. Roofing Specialists Ltd | Construction | 2009 |
| J.B, Viking Building Limited | Construction | 2023 |
| J.C Tiling SW Limited | Construction | 2018 |
| J.Cranfield Plumbing and Heating Ltd | Construction | 2020 |
| J.J. Henry Limited | Real estate | 2006 |
| J.K.E. Holdings Ltd. | Administrative & support | 1990 |
| J.M.C Carpentry & Construction Ltd | Construction | 2025 |
| J.M.W. Limited | Professional & scientific | 1992 |
| J.O.O Investment Properties Ltd | Real estate | 2025 |
| J.Rudgewick Limited | Wholesale & retail | 1955 |
| J2C Clearance Ltd | Water & waste | 2016 |
| J2ESTATES Ltd | Real estate | 2025 |
| J2R Safety Ltd | Construction | 2020 |
| J4KLAAT Limited | Wholesale & retail | 2021 |
| J9 Limited | Wholesale & retail | 1997 |
| Jacile Property and Investments (JPI) Ltd | Real estate | 2025 |
| Jack Sofia Properties Limited | Real estate | 2020 |
| Jacks Instant FIX Limited | Construction | 2022 |
| Jackson Decorating Services Limited | Construction | 2016 |
| Jacksons Train Care Limited | Professional & scientific | 2018 |
| Jacob ID Products Ltd | Wholesale & retail | 2017 |
| Jac’S Agility Ltd | Education | 2025 |
| Jad's Convenience Store Ltd | Wholesale & retail | 2024 |
| Jadaash Limited | Health & social care | 2023 |
| Jadacara Ltd | Health & social care | 2018 |
| Jade African Food Ltd | Hospitality | 2018 |
| Jade Honey Ltd | Real estate | 2020 |
| Jade Stays Limited | Real estate | 2022 |
| Jadoe Limited | Health & social care | 2017 |
| Jaeteg Limited | Health & social care | 2015 |
| JAF IT Consultants UK Ltd | Professional & scientific | 2017 |
| Jaffa MED Ltd | Health & social care | 2026 |
| Jaffar ALI Ltd | Wholesale & retail | 2023 |
| Jagged Limited | Wholesale & retail | 2020 |
| JAGIESKY84 Limited | Health & social care | 2022 |