| J. & M. Parsons Limited | Wholesale & retail | 2002 |
| J. H. Matthew Limited | Real estate | 2005 |
| J. Stone Engineering Limited | Administrative & support | 1982 |
| J.A. Hawkes & SON Investments Limited | Administrative & support | 2000 |
| J.A.Hawkes & SON Limited | Real estate | 1916 |
| J.C. & R.H. Palmer Limited | Manufacturing | 1975 |
| J.C. Phillips & SON Limited | Wholesale & retail | 2002 |
| J.J. Moore (Swanage) Limited | Wholesale & retail | 1980 |
| J.N. Lynch & Sons Limited | Construction | 2002 |
| James Todd & Sons (Textiles) Limited | Wholesale & retail | 1973 |
| James Wilson (Engravers) Limited | Manufacturing | 1971 |
| Jamie LD Wellness Uk/Turkey Ltd | Administrative & support | 2022 |
| Jassim & Khidur Limited | Real estate | 2007 |
| JAY General Trading Ltd | Wholesale & retail | 2024 |
| JB Security Limited | Construction | 2002 |
| Jbvr Ltd | Administrative & support | 2024 |
| Jellis Investments Ltd | Information & communication | 2019 |
| JEM Racing Limited | Real estate | 2005 |
| Jibtek Limited | Other services | 2007 |
| JIM Froud Building Contractor Limited | Construction | 2001 |
| JJK Services Limited | Construction | 2004 |
| JM Pearce Consultancy Ltd | Financial services | 2013 |
| John Bright Fencing Ltd. | Construction | 1999 |
| John LEE & Sons (Ferndown) Limited | Construction | 1952 |
| John Makepeace Limited | Manufacturing | 1965 |
| John Mckeown Consultancy Limited | Health & social care | 2004 |
| John Reid & Sons (International) Limited | Manufacturing | 1978 |
| John Reid & Sons(Strucsteel)Limited | Manufacturing | 1958 |
| John Stanley Transport Limited | Transport & logistics | 2006 |
| Josbon Media Ltd | Professional & scientific | 2021 |
| Jpc's (Bournemouth) Limited | Information & communication | 2007 |
| JT Joinery (Weymouth) LLP | | 2007 |
| Jtix Limited | Wholesale & retail | 2023 |
| Juniortennisstars Ltd | Arts & recreation | 2025 |
| Jurassic Coast Art Limited | Professional & scientific | 2005 |
| Jurassica Park Limited | Hospitality | 2020 |
| Just Joys Limited | Wholesale & retail | 2002 |
| K.H. Electrical Limited | Construction | 2002 |
| K.S. Bevan Limited | Construction | 2006 |
| K4 Interiors Limited | Construction | 2003 |
| Kaemex Ltd | Wholesale & retail | 2024 |
| Kalfaoglu Ltd | Information & communication | 2024 |
| Kavanagh Roofing Limited | Construction | 1986 |
| Kaymech Engineering Limited | Professional & scientific | 2007 |
| Keith Acres Caravan Park Limited | Hospitality | 2003 |
| Keith Motors (Christchurch) Limited | Wholesale & retail | 1964 |
| Kevin Jolly Fencing Limited | Construction | 2005 |
| Keybel Consultants Limited | Information & communication | 2006 |
| KGB Services Limited | Information & communication | 1998 |
| Kilo Victor Bravo Limited | Professional & scientific | 2007 |
| King & Barnes Limited | Extraterritorial | 1893 |
| King Stag (Holdings) Limited | Real estate | 2005 |
| King Stag Limited | Manufacturing | 2002 |
| Kingfisher Developments (UK) Limited | | 1983 |
| Kings Road Cars Ltd | Transport & logistics | 2006 |
| Kingsmill Holdings Limited | Professional & scientific | 2005 |
| Kingston Maurward Enterprises Limited | Arts & recreation | 2005 |
| Kionet Ltd | Information & communication | 1996 |
| Kirkstone Learning Limited | Professional & scientific | 2004 |
| Kirtleton Management Company Limited | Households | 1984 |
| Kitchen Style of Dorchester Limited | Wholesale & retail | 2001 |
| KJC International Limited | Wholesale & retail | 2017 |
| Kljm Limited | Professional & scientific | 2001 |
| KM Construction (Dorset) Ltd | Construction | 2019 |
| Kose London Limited | Information & communication | 2019 |
| KRS Motors Ltd | Other services | 2004 |
| KSL One Limited | Manufacturing | 2013 |
| L D L Homes Limited | | 1985 |
| LA Fleur DE LYS Limited | Hospitality | 2003 |
| Laceys Limited | Professional & scientific | 1988 |
| Laceys Mediation Service Limited | Professional & scientific | 2000 |
| Lailey Limited | Information & communication | 1995 |
| Lake Engineering (Poole) Limited | Manufacturing | 1993 |
| Lakg Limited | Wholesale & retail | 2004 |
| Lampard Electrics Ltd | Construction | 2007 |
| Lancino Limited | Professional & scientific | 1996 |
| Langdon (Dorset) Farms | Agriculture & fishing | 1941 |
| Langfords Vehicle Dismantlers Limited | Wholesale & retail | 2004 |
| Langham Enterprises Limited | Agriculture & fishing | 1982 |
| Langham Farms Limited | Agriculture & fishing | 2003 |
| Lansdowne Woodward Holdings Limited | Professional & scientific | 2007 |
| Lapbulge Limited | Professional & scientific | 1988 |
| Lattice House Properties Limited | Real estate | 1998 |
| Laura Marie Psychotherapy & Counselling Ltd | Health & social care | 2025 |
| Lawtons News Limited | Wholesale & retail | 2003 |
| LB Elevators Limited | Construction | 2005 |
| Leasehold Management Professionals Limited | Education | 2017 |
| Ledgers Accountants Ltd | Professional & scientific | 1985 |
| Leejofa Limited | Wholesale & retail | 1990 |
| Leeline Bodyworks Limited | Wholesale & retail | 1999 |
| Legal Beagles Limited | Professional & scientific | 1986 |
| Leisend Management Limited | Households | 1992 |
| Leveret Developments Limited | Real estate | 1998 |
| Lewis & Co (Investments & Pensions) Limited | Financial services | 1994 |
| Lewis Pension Admin Limited | Financial services | 2006 |
| Libra Homes Limited | Other services | 1996 |
| Libra Land Limited | Administrative & support | 2000 |
| Lilder Builders Limited | Construction | 1967 |
| Lilliput Autistic ABA (Applied Behaviour Analysis) Charity Limited | Education | 1998 |
| Lindark Limited | Extraterritorial | 2000 |