| Redline Haulage UK Limited | Transport & logistics | 1997 |
| Redstone PDM Ltd | Construction | 2016 |
| Reed Comics Limited | Wholesale & retail | 2002 |
| Rega Ventilation Limited | Manufacturing | 1984 |
| Registration Transfers Limited | Wholesale & retail | 2000 |
| Remola Ltd | Transport & logistics | 2007 |
| Rescom Investments Ltd | Real estate | 2002 |
| RGB Freelancers Limited | Other services | 2006 |
| Richard Beaty (Building Design) Limited | Professional & scientific | 1987 |
| Richardson Milling (UK) Limited | Manufacturing | 1984 |
| Rick Adams Plumbing & Heating Limited | Construction | 2007 |
| Ridgeway Bespoke Builds Ltd | Construction | 2024 |
| Right Price Electrical Services Ltd | Construction | 2005 |
| Right Track (Contractors) Limited | Professional & scientific | 2002 |
| Ritchy Management Company Limited | Households | 1993 |
| Riviera Icecream Limited | Extraterritorial | 2000 |
| Robovision Limited | Wholesale & retail | 1986 |
| Robustmind Mental Fitness Ltd | Health & social care | 2015 |
| Roger Mason Limited | Administrative & support | 2002 |
| Ronian Packaging Limited | | 1978 |
| Rosegulf Limited | Manufacturing | 1996 |
| Rowallane Builders Limited | Construction | 2004 |
| Roxton Bar Services Limited | Hospitality | 1997 |
| Rspb Nature Regen Ltd | Real estate | 2023 |
| Ruddy Joinery Limited | Construction | 1978 |
| RWM Taxation Limited | Professional & scientific | 2003 |
| S & D Contracts UK Limited | Construction | 2004 |
| S & M Foodstores Ltd | Wholesale & retail | 2003 |
| S & W Plant Limited | Administrative & support | 2007 |
| S H Pratt Group Limited | Manufacturing | 1959 |
| S Mlotek Consultancy Limited | Wholesale & retail | 2007 |
| S.J. Farrow Construction Limited | | 1998 |
| SAA Radiology Ltd | Health & social care | 2018 |
| Sabert UK Ltd | Manufacturing | 2015 |
| Saeeda Consulting Limited | Information & communication | 2001 |
| Safebuild Installations Limited | Construction | 2002 |
| Safety Belt Services Limited | Manufacturing | 2000 |
| Saltmore Limited | Real estate | 2004 |
| Saraso HR Consulting Ltd | Professional & scientific | 2006 |
| Sarc Construction Limited | Construction | 2004 |
| SAS Fresh Produce LLP | | 2002 |
| Saxon Trailers Limited | | 1993 |
| SCA Group Investments LP | | 2011 |
| Scholten Foods Ltd | Wholesale & retail | 2012 |
| Searchenergy Limited | Administrative & support | 2007 |
| Secureclean Limited | Administrative & support | 1999 |
| Security Contract Consulting Limited | Construction | 2026 |
| Select Plumbing Limited | Construction | 2005 |
| Sense Housing Limited | Real estate | 2022 |
| Serene Management & Consulting Limited | Information & communication | 2007 |
| Serene Technical Services Limited | Construction | 2003 |
| Service Express Europe Limited | Information & communication | 1987 |
| SFV Consulting Limited | Professional & scientific | 2002 |
| Shadowsheep Limited | Information & communication | 2006 |
| SHAMROCK1888 Ltd | Hospitality | 2025 |
| Sharman Law LLP | | 2008 |
| Shefford Hand Laundry Limited | Extraterritorial | 1971 |
| Silver Bullet Construction Ltd | Extraterritorial | 2020 |
| Simflex Grilles and Closures Limited | Administrative & support | 1989 |
| Sky Aviation Limited | Wholesale & retail | 1995 |
| Slovglass Imports Ltd. | Other services | 2000 |
| Softsoft Limited | Information & communication | 1999 |
| South Eastern Produce Limited | Wholesale & retail | 2005 |
| Sovereign Scaffolding Limited | | 2007 |
| SP Felgen Forged Wheels Ltd | Wholesale & retail | 2024 |
| SP Tech Services Ltd | Information & communication | 2022 |
| Sparkle Systems Ltd | Other services | 2005 |
| Specfit Limited | | 1989 |
| Spectra Carpets Limited | Wholesale & retail | 1982 |
| Speed String Ltd. | Other services | 2001 |
| Speedoz Ltd | Wholesale & retail | 2004 |
| Spirekin Ltd | Information & communication | 2005 |
| Sportsmatch U.K. Limited | Professional & scientific | 1972 |
| Stabletree Limited | Construction | 1993 |
| Stage 73 Limited | Information & communication | 2009 |
| Stanley & Lesley Ltd | Hospitality | 2007 |
| Stellco Homes Limited | Extraterritorial | 2003 |
| Sterilization Solutions Limited | Professional & scientific | 2003 |
| Steves Tyres Ltd | Wholesale & retail | 2012 |
| Stewkley Food & Wines Limited | Wholesale & retail | 2014 |
| Stonesby Care Home Ltd | Health & social care | 2024 |
| Stoten Gillam Limited | Professional & scientific | 2002 |
| Stour Valley Limited | Manufacturing | 1984 |
| STS Wheel Alignment Centre & Mechanical Repairs Limited | Wholesale & retail | 2006 |
| Style Inn Hair & Beauty Specialist Limited | Other services | 2016 |
| Succeed With Stacey Ltd | Health & social care | 2025 |
| Sun Realm Heating Co. Limited | Construction | 1975 |
| Sunflower Relief Limited | Financial services | 2022 |
| Sunnah Social Respite CIC | Health & social care | 2025 |
| Supertyres (Luton) Limited | Wholesale & retail | 1966 |
| Swansholme Garden Management Co. Limited | Households | 1978 |
| Swansoft Ltd | Information & communication | 2014 |
| Syncretic Works Ltd | Construction | 2002 |
| T C S Global Limited | Information & communication | 1995 |
| T K OIL Technology Limited | Wholesale & retail | 2002 |
| T. J. Aldridge Builders Limited | Construction | 2002 |
| T.G.M Mortgage Services Limited | Financial services | 2004 |
| TAK Fong Limited | Real estate | 2002 |
| Tal-Ko Racing Limited | Wholesale & retail | 2002 |
| Task Automation Limited | Professional & scientific | 2005 |