| H.Q. Forklifts Limited | Wholesale & retail | 2013 |
| Haddenham Green Management Co. Limited | Real estate | 1987 |
| Hadlow Surveys Ltd | Professional & scientific | 2011 |
| Hair & Beauty Hub March Limited | Wholesale & retail | 2015 |
| Hair at the Atrium Limited | Other services | 2003 |
| Hall Farm Livery Stables Ltd | Agriculture & fishing | 2021 |
| Halstead Energy Limited | Administrative & support | 2017 |
| Hard Times Clothing Limited | Wholesale & retail | 2014 |
| Harmony Home Care Services Ltd | Health & social care | 2026 |
| Harradine Property Letting Ltd | Real estate | 2011 |
| Harrison Holdings (March) Ltd | Financial services | 2026 |
| Harrison Properties (March) Ltd | Real estate | 2026 |
| Harrison Tractors Ltd | Wholesale & retail | 2009 |
| Harry Turner Creative Ltd | Professional & scientific | 2016 |
| Hart Engineering Limited | Construction | 1999 |
| Hazelwood Landscaping Services Ltd | Administrative & support | 2024 |
| Hbsl Energy Management Ltd | Administrative & support | 2018 |
| Head of Electrics Ltd | Construction | 2026 |
| Headway Cambridge and Peterborough Limited | Health & social care | 2023 |
| Hearn Engineering Services Limited | Professional & scientific | 2019 |
| Heatherbell Estates Ltd | Real estate | 2006 |
| Heltrion Ltd | Information & communication | 2026 |
| Hemp Herb CBD Ltd | Wholesale & retail | 2026 |
| Hepple&Emmott RTM Company Limited | Households | 2019 |
| Hermitage Gardens Management Limited | Households | 2018 |
| Heron Investments Limited | Real estate | 1999 |
| Hiaks Recycling Ltd | Manufacturing | 2020 |
| Highfield Plant & Suction Ltd | Construction | 2026 |
| Hill Farm Properties Ltd | Real estate | 2020 |
| Hillfarmgoodies Limited | Wholesale & retail | 2023 |
| HJC Construction Ltd | Professional & scientific | 2023 |
| HLK Property Services Ltd | Professional & scientific | 2023 |
| Holt Power Limited | Construction | 2024 |
| Homestone UK - Natural and Semi-Precious Stones for the Building Trade Ltd | Wholesale & retail | 2022 |
| Hoodsport (Soham) Limited | Construction | 2017 |
| Hoop-Dee-Doo Ltd | Information & communication | 2024 |
| Horse Creek Farms Limited | Arts & recreation | 2007 |
| Howden Aviation Ltd | Transport & logistics | 2023 |
| HSH Furniture Ltd | Wholesale & retail | 2024 |
| HSR Electrical Solutions Ltd | Construction | 2019 |
| Hubpartners Limited | Extraterritorial | 1961 |
| HUE Heating & Cooling Ltd | Professional & scientific | 2024 |
| Hugh Brooks Consulting Ltd | Information & communication | 2024 |
| Hyper Engineering Ltd | Manufacturing | 2023 |
| IAN Gowler Consulting Ltd | Professional & scientific | 2016 |
| IDT Construction Ltd | Construction | 2016 |
| Idtg Ltd | Information & communication | 2023 |
| Iema Sustainability Training Solutions Ltd | Professional & scientific | 2013 |
| Impala Electrical Services Limited | Construction | 2015 |
| Indigo Top Ltd | Financial services | 2026 |
| Innoveta Capital Ltd | Financial services | 2025 |
| Innoveta Ltd | Information & communication | 2023 |
| Inovai Ltd | Information & communication | 2025 |
| Insane Terrain Running Limited | Arts & recreation | 2012 |
| Insulated Construction Group Limited | Construction | 2018 |
| Intelligent Optical Solutions Ltd | Other services | 2023 |
| Istanbul Barber 2 Ltd | Other services | 2020 |
| Italian Pizza High Street Limited | Hospitality | 2025 |
| Ivel Ltd | Transport & logistics | 2019 |
| J & C Transport Ltd | Transport & logistics | 2016 |
| J & N Brickwork Ltd | Construction | 2023 |
| J & S World Food Supplies Ltd | Wholesale & retail | 2023 |
| J Brownlow Limited | Construction | 2008 |
| J E Electrical Services Limited | Construction | 2018 |
| J G Mason Sub-Contractors Groundwork Services Limited | Construction | 2005 |
| J M Mckay Builders Ltd | Construction | 2021 |
| J M R Utilities Ltd | Construction | 2022 |
| J.C.Martin (Farms) Limited | Agriculture & fishing | 1959 |
| J.M. Automotive Specialist Ltd | Wholesale & retail | 2019 |
| J.T. Clarke (March) Limited | Agriculture & fishing | 1977 |
| Jack's Precision Refinishing Limited | Wholesale & retail | 2026 |
| Jaffaranch Limited | Professional & scientific | 1984 |
| Jals Mechanical Services Ltd | Professional & scientific | 2025 |
| Javevent Limited | Agriculture & fishing | 2009 |
| Jcat Developments Limited | Manufacturing | 2008 |
| JCM Commissioning & Water Treatment Ltd | Construction | 2019 |
| JDH Electrical Services Ltd | Construction | 2017 |
| Jean Grima BIA Ltd | Health & social care | 2025 |
| JEM Mortgages Limited | Financial services | 2018 |
| JF Flat Roofing Ltd | Construction | 2023 |
| Jg.Renovations&Lettings Ltd | Real estate | 2025 |
| JLP Utilities Ltd | Real estate | 2026 |
| JM Utility Services Ltd | Professional & scientific | 2017 |
| Johan Smalman Dentist Limited | Health & social care | 2009 |
| JOM Solutions Limited | Administrative & support | 2025 |
| JRK & Partners Limited | Other services | 2006 |
| JS & MJ Cook Storage Limited | Transport & logistics | 2017 |
| Jubilee Developments Limited | Construction | 2016 |
| Jubilee Leases Ltd | Financial services | 2021 |
| Justmaker Limited | Real estate | 1987 |
| JW Transport and Warehousing Consultancy Ltd | Transport & logistics | 2025 |
| Jwc&Hg Ltd | Professional & scientific | 2023 |
| K & B Civils Ltd | Professional & scientific | 2022 |
| K. M. Keogh Limited | Construction | 2013 |
| K.E. Rolfe Independant Funeral Directors Ltd | Other services | 2025 |
| Kanakan Services Limited | Wholesale & retail | 2017 |
| Karutis Parts Ltd | Wholesale & retail | 2024 |
| Kashmir and Pizza Limited | Hospitality | 2024 |
| KCB Property Lettings Ltd | Real estate | 2025 |
| KD Building Maintenance and Refurbishing Ltd | Construction | 2025 |