| Fred Kidd & SON (Engineers) Limited | | 1939 |
| Freeman, Volkers & Stuart Limited | Transport & logistics | 1975 |
| Fulcrum Medical Practice LLP | | 2006 |
| G Pacitto & Sons (Redcar) Limited | Manufacturing | 1998 |
| Gary Nelson Tankers Limited | Transport & logistics | 2001 |
| Graythorpe Forge and Engineering Limited | Manufacturing | 2004 |
| Greco Brothers Limited | Manufacturing | 1947 |
| Greenfix Soil Stabilisation & Erosion Control Limited | Wholesale & retail | 2007 |
| Greg Malloy Limited | Other services | 2007 |
| Greylin Engineering Limited | Manufacturing | 1976 |
| Grosvenor Investigations & Security Services Limited | Administrative & support | 2003 |
| Groveport Pension Trustees Limited | Professional & scientific | 1991 |
| Guaco Limited | Extraterritorial | 2004 |
| Guido's Hair Limited | Other services | 2002 |
| Guisborough & District Motor Cycle Club Limited | Arts & recreation | 1979 |
| GUL Consultants Limited | Health & social care | 2007 |
| GW Leader (Holdings) Limited | Professional & scientific | 2002 |
| H & a Height Services Ltd. | Construction | 1965 |
| H & D Sales | | 1990 |
| Hackett (Bolts & Nuts) Limited | | 1934 |
| Hairtek Limited | Other services | 2002 |
| Handley Business Services Limited | Arts & recreation | 2006 |
| Hank Sharpe (Travel) Limited | Administrative & support | 1972 |
| Hannu Developments Limited | Information & communication | 1996 |
| Harpers Property & Landscape Limited | Real estate | 2007 |
| Hart Industrial Tools Limited | Manufacturing | 2003 |
| Hartlepool Design Services Ltd | Other services | 2007 |
| Hartlepool Yacht Club Limited | Arts & recreation | 1983 |
| Hazel Towers Company Limited | Households | 1991 |
| Hiphie Limited | Wholesale & retail | 2026 |
| HL News & Cards Limited | | 2005 |
| Hobsons Wholesale (Cleveland) Limited | Wholesale & retail | 1976 |
| Holga Limited | Other services | 2000 |
| Home Bakery (Saltburn) Limited | | 1975 |
| Honey LEA Beatrice Limited | Wholesale & retail | 2025 |
| Hornsey Investments Limited | Real estate | 1978 |
| Housams (1985) Limited | Wholesale & retail | 1984 |
| I.S.V. Clearview Limited | Real estate | 1994 |
| Industrial Control Electronics Limited | Administrative & support | 1990 |
| Integrated Business Solutions Limited | Professional & scientific | 2004 |
| Internet Intranet Resourcing Consultancy Limited | Information & communication | 1996 |
| Ironpride Limited | Professional & scientific | 1983 |
| J'S Gents Hairdressing Limited | Other services | 2001 |
| J. H. Fawcett Limited | Wholesale & retail | 1963 |
| Jack Brunton & Partners | | 1986 |
| Jagtech Limited | Wholesale & retail | 2005 |
| Jchem Design Limited | Professional & scientific | 2005 |
| John B.Smith Limited | Manufacturing | 1946 |
| John Livingston & Sons Holdings Limited | Professional & scientific | 2007 |
| John Livingston (Estates) Holdings Limited | Professional & scientific | 2007 |
| Jonathan Spencer Consultants Limited | Professional & scientific | 2003 |
| JP Software Services Limited | Information & communication | 1989 |
| JSL Vehicle Repair Centre Ltd | Wholesale & retail | 2003 |
| K. & P. Anderson Bros. (Coachworks) Limited | Wholesale & retail | 1979 |
| Kake Kraft Limited | Manufacturing | 2006 |
| Kaskane Holiday Cottages Limited | Real estate | 2007 |
| Katmex Limited | Manufacturing | 1999 |
| KI Graham Limited | Administrative & support | 2006 |
| KIE Project Services Limited | Other services | 2023 |
| Kiplun Limited | Professional & scientific | 2005 |
| Kirsty Louise Limited | Wholesale & retail | 2025 |
| Kowbe Custom Ltd | Manufacturing | 2022 |
| KW Competencies Limited | Professional & scientific | 2021 |
| Kwikbizz Limited | Professional & scientific | 2004 |
| Kyle Valley (Farms) Limited | | 1974 |
| L.M.& C. Accounting Services Ltd. | Professional & scientific | 1987 |
| Landen Investments Limited | Real estate | 2003 |
| Lawson Cars Limited | Wholesale & retail | 2000 |
| Leader Online Limited | Wholesale & retail | 2006 |
| Linxport Limited | Transport & logistics | 2023 |
| Lockmel Limited | Information & communication | 1989 |
| Lognat Limited | Households | 1989 |
| Lucava Limited | Construction | 2019 |
| M N G (UK) Limited | Professional & scientific | 2005 |
| M. Taylor Limited | Professional & scientific | 2006 |
| M.A.G Lifting Specialists Ltd | Professional & scientific | 2017 |
| Macaulay Lennon Limited | Wholesale & retail | 2025 |
| Malcolm Keegan Electrical Containment Ltd | Construction | 2016 |
| Malvern Services Ltd | Transport & logistics | 2003 |
| Matthew Robinson Engineering Limited | Professional & scientific | 2007 |
| Maval Engineering Company Limited | Manufacturing | 1966 |
| MB DIY Limited | Wholesale & retail | 2016 |
| Mcaveeney Limited | Wholesale & retail | 2025 |
| MCS Computers Limited | Professional & scientific | 2004 |
| Mensco Limited | | 1988 |
| Mercury Technologies Limited | Professional & scientific | 2000 |
| Mesh Group Limited | Financial services | 2025 |
| Middlesbrough Insulation Company Limited | Construction | 1976 |
| Middlesbrough Specsavers Limited | Wholesale & retail | 1986 |
| Middlesbrough Visionplus Limited | Wholesale & retail | 1995 |
| Mids Auto Services Limited | Wholesale & retail | 2003 |
| Mike Taylor Developments Limited | Real estate | 1976 |
| Minhoco 89 Holding Ltd | Health & social care | 2024 |
| Minhoco 90 Holdco Ltd | Health & social care | 2024 |
| Mistell Limited | Hospitality | 2005 |
| MJ Quality Assurance Consultant Limited | Professional & scientific | 2005 |
| MJS Projects Limited | Construction | 2006 |
| ML Consultants (NE) Limited | Administrative & support | 2007 |
| Moorehead Sutton & Laing Limited | Professional & scientific | 1997 |
| Moores Leisure (Teesside) Limited | Hospitality | 1995 |