| Isometrix Lighting &DESIGN LimitedLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1992 |
| Italia Wine and Food LtdUnited Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2018 |
| Italian Food Holding LtdLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2021 |
| Italtaste LimitedWoking, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2010 |
| Iveria Wines LtdLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2025 |
| J & C Omeara LtdBurscough, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1990 |
| J & de LtdMarket Harborough, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2017 |
| J A Rose LtdMacclesfield, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2009 |
| J Chandler & Co LtdAndover, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1927 |
| J D Wetherspoon PLCWatford, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1983 |
| J V International LtdWilmslow, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2006 |
| J&B Selections LtdLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2025 |
| J. Davidson Scrap Metal Proc Essors LimitedAltrincham, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2011 |
| J.c. Bamford Excavators LimitedUttoxeter, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1956 |
| Jab Partners LimitedLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2021 |
| Jack Nadel International LtdLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2000 |
| Jacquart UK LimitedLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2024 |
| Jakmob International LimitedCroydon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2012 |
| Jaks Bars & Restaurants LtdLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2010 |
| James Boylan Safety LtdOmagh, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1958 |
| Jane Street Europe LtdLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2006 |
| Jazz Pharmaceuticals UK LtdLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2002 |
| Jba Corporation LtdPrinces Risborough, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2017 |
| Jellysmack LimitedWyboston, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2020 |
| Jenner and Block London LLPNew Castle, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2023 |
| Jenny Beavan Designs LimitedWorthing, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2004 |
| Jetvine Consultancy LtdWalton-on-Thames, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2020 |
| Jfc LimitedHayes, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1992 |
| Jimmy Products UK LimitedRetford, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2020 |
| Joi Productions LimitedLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2016 |
| Jp Fine Wines LtdChalgrove, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2025 |
| Jt Man Group LtdManchester, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2024 |
| Juergen Teller LtdLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2001 |
| Juls London LimitedLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2022 |
| Junkwize LtdWimbledon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2012 |
| Kaboodle Solutions LtdManchester, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2015 |
| Kalita Clothing LimitedLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2016 |
| Kalkedon LimitedEdinburgh, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2019 |
| Kangaroo International Express LtdPoyle, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1989 |
| Karafe LimitedLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2020 |
| Keating Chambers Service Company LtdLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2004 |
| Keepit Technologies UK, LtdLondon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2021 |
| Kellars LimitedShildon, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2001 |
| Kent St Wines UK LtdHayes, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2011 |
| Kerzner International Marketing LimitedKnightsbridge, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1985 |
| Khoki United LimitedBushey, United Kingdom · UKkhokiunited.com · checked 28 Oct 2026 | UK | 1 | – | – | – | – | 2022 |
| Kilfinichen Farms LimitedWickford, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 1989 |
| Kimm & Miller LtdBedford, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2006 |
| Koru Liquor Brands Sourcing LtdDunmow, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2019 |
| Kuredo Group LtdLeamington Spa, United Kingdom · UKchecked 28 Oct 2026 | UK | 1 | – | – | – | – | 2020 |