| Ipsum Water (England & Wales) Limited | Financial services | 2013 |
| IQ Business Innovations Limited | Information & communication | 2023 |
| Iqgo Ltd | Wholesale & retail | 2019 |
| Irenovate Eyelash Extensions Limited | Other services | 2018 |
| Ireview Ltd | Financial services | 2018 |
| IRJ Surveys & Valuations Ltd | Other services | 2014 |
| Ironstone Projects Limited | Professional & scientific | 2019 |
| Irvine Properties (Lancashire) Limited | Real estate | 2017 |
| Isaac B Builders Ltd | Construction | 2025 |
| Ischio Ltd | Health & social care | 2025 |
| Isentra Ltd | Manufacturing | 2015 |
| Isla Holdings (Chorley) Limited | Real estate | 2023 |
| ISN Investments Ltd | Financial services | 2022 |
| ISN Property Holdings Ltd | Real estate | 2023 |
| ISNAG4U Ltd | Professional & scientific | 2021 |
| Isolinear Consultancy Ltd | Information & communication | 2025 |
| Istox Ltd | Households | 2011 |
| IT Fitz Limited | Real estate | 2004 |
| IT Hummingbird Limited | Information & communication | 2012 |
| IT Management & Support Limited | Information & communication | 2014 |
| IT Support 365 Ltd | Information & communication | 2008 |
| It's Mental Limited | Health & social care | 2022 |
| Ivanthais Ltd | Construction | 2019 |
| IVY Housing & Lettings Limited | Real estate | 2023 |
| Izza Care Ltd | Health & social care | 2020 |
| J & B Escapes Limited | Wholesale & retail | 2025 |
| J & G Entrances Ltd | Construction | 2019 |
| J & J King Construction/Groundwork Ltd | Construction | 2024 |
| J & J Stevenson GT Ltd | Administrative & support | 2012 |
| J & K Building Services UK Ltd | Construction | 2016 |
| J & M Civil Engineering Limited | Construction | 2014 |
| J & M Demolition and Recycled Aggregates Limited | Construction | 2017 |
| J & M Euxton Ltd | Hospitality | 2021 |
| J & P Bespoke Construction & Joinery Ltd | Construction | 2018 |
| J & P Pubs and Taverns Ltd | Hospitality | 2024 |
| J & R Property Portfolio Limited | Real estate | 2018 |
| J & S Landscapes & Resin Surfacing (NW) Ltd | Administrative & support | 2026 |
| J a Parker Consulting Ltd | Financial services | 2015 |
| J and M Properties (Chorley) Limited | Real estate | 2016 |
| J B Loughlin (Contractors) Limited | Construction | 1995 |
| J Blackwell Plumbing & Heating Limited | Construction | 2002 |
| J Bolton Construction Ltd | Construction | 2010 |
| J Bowler Building Services Ltd. | Construction | 2020 |
| J Brown Construction Agriculture Ltd | Agriculture & fishing | 2014 |
| J Drinkall Limited | Agriculture & fishing | 2002 |
| J EHI Ltd | Health & social care | 2017 |
| J Hulbert Core Financial Services Limited | Professional & scientific | 2010 |
| J I Roden Bricklaying and Building Limited | Construction | 2009 |
| J J Fencing Ltd | Manufacturing | 2025 |
| J L West Construction Ltd | Construction | 2022 |
| J M Construction & Heating Ltd | Construction | 2025 |
| J P & G Services Ltd | Construction | 2011 |
| J P Boardman & Co Limited | Professional & scientific | 2008 |
| J P Dance Promotions Limited | Arts & recreation | 2019 |
| J P Estates LLP | | 2011 |
| J P Machinery Sales Ltd | Wholesale & retail | 2025 |
| J Quinn Services Limited | Construction | 2022 |
| J Rose Care Limited | Real estate | 2015 |
| J S Stokes Holdings Limited | Financial services | 2009 |
| J Sharples Joinery & Building Services Ltd | Construction | 2017 |
| J T Waugh Property Limited | Construction | 2021 |
| J Wilson Property Ltd | Real estate | 2018 |
| J&N T/A Uncle JIM Ltd | Hospitality | 2016 |
| J&T Catering Ltd | Hospitality | 2021 |
| J. a. Jackson Building Contractors Limited | Construction | 2002 |
| J. Charnley & Sons | Manufacturing | 1999 |
| J. Gilman's SON and Granddaughters Limited | Other services | 2003 |
| J. Hudson Asset Holdings Limited | Real estate | 2026 |
| J. P. Properties (Wigan) Limited | Real estate | 2004 |
| J.C Agricultural Ltd | Wholesale & retail | 2020 |
| J.C Kilner Limited | Construction | 2009 |
| J.M. Pearce Displays (Huddersfield) Limited | Manufacturing | 1979 |
| J.Mallinson (Ormskirk) Limited | Construction | 1961 |
| J.Moore Classic Cars Limited | Wholesale & retail | 2017 |
| J.S & D.M Ltd. | Wholesale & retail | 2017 |
| J.S. Stokes Properties Limited | Construction | 1988 |
| J.S.Stokes & Co. Limited | Financial services | 1963 |
| J.T. Holding & SON Limited | Construction | 2010 |
| J.Wrennall Agri & Plant Engineering Ltd | Professional & scientific | 2026 |
| Jaaam Radiology Services Ltd | Real estate | 2020 |
| Jabern Properties Limited | Professional & scientific | 2013 |
| JAC Lifts Limited | Construction | 2010 |
| Jack Clark Carpentry & Building Ltd | Manufacturing | 2019 |
| Jack Media Oxfordshire Limited | Information & communication | 1996 |
| Jack Spratt Baby Ltd | Wholesale & retail | 2015 |
| Jackson Jones Inns Ltd | Hospitality | 2022 |
| Jacksons Blackpool Property Limited | Real estate | 2019 |
| Jade Liquor Distillers Ltd | Manufacturing | 2024 |
| Jade Vose Psychological Services Ltd | Health & social care | 2026 |
| Jakane Ltd | Health & social care | 2024 |
| Jalfine Ltd | Professional & scientific | 2020 |
| Jalisco (Brixton) Limited | Hospitality | 2013 |
| JAM Properties Ltd | Real estate | 2025 |
| Jam's Chippy Limited | Hospitality | 2024 |
| James Ashworth Haulage Limited | Transport & logistics | 2015 |
| James Booth Electrical Ltd | Construction | 2018 |
| James E. Hatch & SON LLP | | 2002 |
| James Electrical (NW) Ltd | Manufacturing | 2007 |
| James Electrical NW Services Ltd | Manufacturing | 2023 |
| James Esdaile Limited | Extraterritorial | 2010 |