| Haro OIL Limited | Manufacturing | 1994 |
| Harrison and Simmonds Limited | Wholesale & retail | 2005 |
| Harvard Way Residents' Management Company Limited | Households | 2015 |
| Hayward Tyler Group Limited | Professional & scientific | 1996 |
| Hayward Tyler Holdings Limited | Professional & scientific | 1996 |
| Hayward Tyler Limited | Manufacturing | 1997 |
| HAZ Building Contractors Limited | Construction | 2002 |
| HDB Associates Ltd | Information & communication | 2006 |
| Helen Hardy Consulting Limited | Information & communication | 2005 |
| Hemmingford Management Limited | Professional & scientific | 1996 |
| Hennelly Construction Limited | | 1988 |
| Herculean Building Company Limited | Professional & scientific | 1977 |
| Herts Glass Company Limited | Real estate | 1968 |
| Hfmd Limited | Health & social care | 2007 |
| Hillside Accounting Services Limited | Professional & scientific | 2020 |
| Hiltstow Limited | | 1972 |
| Hing Eyecare (Shefford) Limited | Health & social care | 2003 |
| HIR Properties Ltd | Real estate | 2023 |
| Hollands Smith Limited | Real estate | 2007 |
| Holts Electrical Limited | Construction | 2003 |
| Homelink Property Services Limited | Real estate | 2007 |
| Horrox Property Ltd | Real estate | 2020 |
| Hotel Discount Codes Ltd | Other services | 2019 |
| Housescape Architectural Limited | Construction | 2005 |
| HOW END Livery Ltd | Agriculture & fishing | 2009 |
| Howard Marine Sales Ltd | Wholesale & retail | 2001 |
| Hr-Blossoms Ltd | Administrative & support | 2020 |
| Hsts Taekwon-Do Limited | Arts & recreation | 2007 |
| Huntree Fencing Limited | Agriculture & fishing | 1983 |
| HZ Electrical Services Limited | Construction | 2007 |
| I B Hyde & SON Limited | Construction | 2002 |
| IAF Services Limited | Construction | 2002 |
| Iboxingtickets.Com Ltd | Administrative & support | 2017 |
| Icknield Builders Limited | Construction | 1962 |
| IK Holdings Ltd | Extraterritorial | 2015 |
| Image Evolution Limited | Manufacturing | 2002 |
| Impex Micro Products Limited | | 1983 |
| IN DA Zone Media Ltd | Arts & recreation | 2004 |
| Inca Pixmore Limited | Manufacturing | 2000 |
| Independent Banking Consultants Limited | Financial services | 2000 |
| Industrial Robotics and Electrical Services Limited | Information & communication | 1999 |
| Infotrain Services Limited | Administrative & support | 2003 |
| Intaglio Solutions Limited | Information & communication | 1999 |
| Interphase Cable Communications Ltd. | Information & communication | 2007 |
| Intrade (GB) Limited | Wholesale & retail | 2001 |
| Intrepid Systems Limited | Manufacturing | 2007 |
| Iris Designs Limited | Professional & scientific | 2002 |
| IT Innovative Solutions Ltd | Information & communication | 2014 |
| Ivel Design Limited | Professional & scientific | 2007 |
| Ivorybridge Limited | Manufacturing | 2004 |
| J & C Flanagan Construction Ltd | Construction | 2005 |
| J & J Architectural and Construction Services Limited | Professional & scientific | 2001 |
| J E R Developments Limited | Construction | 2001 |
| J W M Group Limited | Professional & scientific | 1982 |
| J&J Luxford Limited | Construction | 2004 |
| J.M.S. Control Systems Limited | | 1989 |
| J.R. Kelly Transport Limited | Information & communication | 1978 |
| Jackson & Phillips Automotive Services Ltd. | Wholesale & retail | 1996 |
| Jadewell (U.K.) Limited | Professional & scientific | 1998 |
| Jagtar Singh Associates Limited | Administrative & support | 2005 |
| Jayden Associates Limited | Real estate | 2003 |
| Jaylin Limited | Hospitality | 2014 |
| Jeff Grout Consulting Limited | Professional & scientific | 2005 |
| Jemc Developments Limited | Real estate | 2021 |
| JIM Rumley Associates Limited | Professional & scientific | 2007 |
| JOE Graham & SON Limited | Wholesale & retail | 1994 |
| John Brennan & SON Contractors Ltd | Construction | 2004 |
| John Edgell Limited | Professional & scientific | 2003 |
| John Medhurst Limited | Wholesale & retail | 2002 |
| John Tizard Limited | Administrative & support | 2007 |
| John Woodward Limited | Construction | 1964 |
| Jonathan Vowles Business Services Ltd | Professional & scientific | 1998 |
| Joyner Trucking Limited | | 1980 |
| JP Hygiene Supplies Ltd | Wholesale & retail | 1998 |
| JTR (UK) Limited | Arts & recreation | 2006 |
| K. Wilson Associates Limited | Professional & scientific | 2006 |
| Kalji Limited | Agriculture & fishing | 2002 |
| KAS Paper Systems Limited | Manufacturing | 1953 |
| Keegan Landscaping Ltd | Administrative & support | 2022 |
| Kensal Wireways Limited | Administrative & support | 2002 |
| Kensworth Autos Ltd | Wholesale & retail | 2019 |
| KGD Consulting Ltd | Information & communication | 2006 |
| Kids OUT Trading Limited | Other services | 2002 |
| Kids OUT UK | Administrative & support | 1998 |
| Kimbolton Engineering Limited | Construction | 1991 |
| Kindale Enterprises LLP | | 2005 |
| Kindale Investments Limited | Real estate | 1994 |
| Kindale Limited | Real estate | 1976 |
| King Street Company Directors Limited | Administrative & support | 1997 |
| King Street Secretaries Limited | Administrative & support | 1997 |
| Kirkstone Properties Limited | Construction | 1993 |
| Knight International Properties Limited | Real estate | 2007 |
| Knox Aviation Ltd | Transport & logistics | 2003 |
| KNP Finishing Limited | Manufacturing | 1983 |
| Krusoe & Co. (U.K.) Limited | Wholesale & retail | 1976 |
| KTS Autos Ltd | Wholesale & retail | 2016 |
| L.G.S. Construction Services Limited | Wholesale & retail | 1986 |
| L.W. Vass Limited | Wholesale & retail | 1938 |
| LA Diamond Trading Ltd | Administrative & support | 2019 |
| Lambda Accounts Limited | Information & communication | 2002 |