| Intertek Secretaries Limited | Other services | 1994 |
| Intertek Testing & Certification Limited | Professional & scientific | 1996 |
| Intertek Testing and Inspection Services UK Limited | Professional & scientific | 2013 |
| Intertek Testing Management Ltd | Administrative & support | 1969 |
| Intertek Testing Services Caleb Brett Egypt Limited | Administrative & support | 1954 |
| Intertek Testing Services Holdings Limited. | Administrative & support | 1996 |
| Intertek UK Holdings Limited | Professional & scientific | 1942 |
| Intertek USD Finance Ltd | Professional & scientific | 2011 |
| Interventional Spine & Pain Practice Limited | Extraterritorial | 2020 |
| Interverse Limited | Administrative & support | 2018 |
| Interwines Ltd | Wholesale & retail | 2017 |
| Intex Refurbishments Limited | Construction | 2004 |
| Intimate Apparel Samples Limited | Administrative & support | 2022 |
| Investment Solutions Consultancy Services LLP | | 2019 |
| Investment Solutions Consultant Services Limited | Extraterritorial | 2005 |
| Investment Solutions Consultants Limited | Financial services | 2012 |
| Invisibletiepin Ltd | Wholesale & retail | 2024 |
| Ioannis Limited | Administrative & support | 2017 |
| ION Brothers Ltd | Construction | 2025 |
| Iotatech Limited | Information & communication | 2016 |
| Iotatech Saas Limited | Information & communication | 2023 |
| Ipex Investments Limited | Administrative & support | 2007 |
| Irfanstack Limited | Wholesale & retail | 2025 |
| Iron Rose Investments Ltd | Real estate | 2021 |
| Ironbark Development Ltd | Construction | 2026 |
| Iros Limited | Wholesale & retail | 2004 |
| Irvine Build Limited | Construction | 2014 |
| Isar Solutions Limited | Professional & scientific | 2023 |
| Islabelle Limited | Wholesale & retail | 2023 |
| Island Contracts Ltd | Construction | 2002 |
| Isle of Wight Damp Proofing and Plastering Solutions Limited | Construction | 2021 |
| Isle of Worms CIC | Education | 2023 |
| Isoftdev Ltd | Information & communication | 2025 |
| Ispp Limited | Health & social care | 2020 |
| IT Logistics Global Limited | Information & communication | 2025 |
| ITA Consultancy Limited | Professional & scientific | 2019 |
| Italica Links Ltd | Real estate | 2010 |
| ITD UK Limited | Information & communication | 1999 |
| ITS Testing Services (UK) Limited | Professional & scientific | 1979 |
| ITT Software Ltd | Information & communication | 2026 |
| It’Sawedding Ltd | Arts & recreation | 2023 |
| Iuveni Hair Products UK Ltd | Other services | 2025 |
| Iventura Limited | Information & communication | 2022 |
| IVO Isadore Limited | Administrative & support | 2026 |
| Ivory Hair and Beauty Ltd | Other services | 2022 |
| Ivory Hairdressing Ltd | Other services | 2016 |
| Ivory Rose Care Ltd. | Administrative & support | 2018 |
| IVY Catering Limited | Wholesale & retail | 2019 |
| Ixceed Health UK Ltd | Information & communication | 2017 |
| Ixus Solutions Limited | Administrative & support | 2020 |
| J & AMA Associates Limited | Administrative & support | 2016 |
| J & L Coster (Drainage) Limited | Construction | 2001 |
| J & L Davison Plumbing Limited | Construction | 2015 |
| J & R Builders and Developments Limited | Construction | 1986 |
| J a Mcglynn Consulting Limited | Other services | 2026 |
| J B E Price Ltd | Other services | 2025 |
| J B Electricians Ltd | Construction | 2018 |
| J Berry Contracts Limited | Construction | 2008 |
| J Bishop Properties Limited | Real estate | 2019 |
| J Clark Developments Ltd | Construction | 2018 |
| J Clark Properties Ltd | Real estate | 2024 |
| J F T Property Investments Limited | Real estate | 2010 |
| J G Tiling & Bathrooms Ltd | Construction | 2023 |
| J Gordon Holdings Ltd | Financial services | 2023 |
| J Gordon Properties Ltd | Real estate | 2022 |
| J H Roofing Associates Limited | Construction | 2020 |
| J Hunt Properties Limited | Real estate | 2024 |
| J J Disney Limited | Administrative & support | 2005 |
| J Jones Flooring Contractors Limited | Construction | 2017 |
| J L & B Computer Services Limited | Information & communication | 1995 |
| J Pateman Financial Services Ltd | Professional & scientific | 2020 |
| J Rattledge Ltd | Construction | 2017 |
| J T Murray Ltd | Professional & scientific | 2019 |
| J W Taylor Jewellers Limited | Wholesale & retail | 2002 |
| J Whites Plumbing & Heating Limited | Construction | 2021 |
| J&F Tech Limited | Wholesale & retail | 2020 |
| J&K Dulay Holdings Ltd | Real estate | 2024 |
| J&Lm Consultants Ltd | Administrative & support | 2025 |
| J&N Contractors (Essex) Ltd | Construction | 2018 |
| J&S Brentwood Ltd | Wholesale & retail | 2022 |
| J&S Healthcare Limited | Health & social care | 2007 |
| J-R&Tai Ltd | Health & social care | 2022 |
| J. a. E. Electrical Limited | Other services | 2007 |
| J. Dunton Associates Limited | Professional & scientific | 2003 |
| J. Inkster (Little Park) Limited | Wholesale & retail | 1979 |
| J.C. Coster (Metalworks) Limited | Construction | 2000 |
| J.D.Hare Services Limited | Construction | 2005 |
| J.E.L.D Properties Ltd | Real estate | 2024 |
| J.England Environmental Services Ltd | Administrative & support | 2000 |
| J.F. Fixtures Limited | Professional & scientific | 2024 |
| J.M.G. Windows & Maintenance Limited | Construction | 2005 |
| J.R. Anderson Limited | Professional & scientific | 2015 |
| J3LI Ltd | Manufacturing | 2023 |
| Jack Bass Limited | Construction | 2018 |
| Jack Chinn Sound Ltd | Administrative & support | 2016 |
| Jack O'Keefe Ltd | Professional & scientific | 2021 |
| Jack Young Interiors Limited | Construction | 2017 |
| Jackal Media Ltd. | Information & communication | 2016 |
| Jackjoe Marketing Ltd | Administrative & support | 2010 |
| Jade Foods PVT Ltd | Wholesale & retail | 2022 |