| HackerOne B.V. | London | A rating |
| HackerRank UK Limited | London | A rating |
| Haemonetics Limited | Glasgow | A rating |
| Hafele U.K. Limited | Rugby | A rating |
| HAFIZ MUSTAFA 1864 LONDON LTD | London | A rating |
| Hager Engineering Limited | Telford | A rating |
| Hagerty International Limited | Towcester | A rating |
| HAIER HVAC SOLUTIONS UK LTD | Warrington | A rating |
| Haier Smart Home UK&I Ltd | Warrington | A rating |
| HAINAN AIRLINES HOLDING (UK) CO. LIMITED | London | A rating |
| Haitong International (UK) Limited | London | A rating |
| Hakkasan Limited | London | A rating |
| Hakluyt & Company Limited | London | A rating |
| Haldex Brake Products Limited | Nuneaton | A rating |
| HALEON UK SERVICES LIMITED | Weybridge | A rating |
| Halfords Media UK Limited | London | A rating |
| Hall & Partners Europe Limited | London | A rating |
| Halliburton Manufacturing and Services Limited | Aberdeen | A rating |
| Halliburton Manufacturing and Services Ltd | London | A rating |
| Hallite Seals International Limited | Hampton | A rating |
| Hallmark Cards Plc | Bradford | A rating |
| Halma Plc | Amersham | A rating |
| Halton Foodservice Ltd | Rochester | A rating |
| HAMAMATSU PHOTONICS UK LIMITED | Welwyn Garden City | A rating |
| Hamble Aerostructures Limited | Southampton | A rating |
| Hamilton Hotel Partners Limited | Chelmsford | A rating |
| Hamilton Lane (UK) Limited | London | A rating |
| Hammer Creative Ltd | London | A rating |
| Hammerson Plc | London | A rating |
| Hammertech Software UK Ltd | London | A rating |
| Hampton Group International Ltd | London | A rating |
| Hana Group UK Limited t/a Sushi Gourmet | London | A rating |
| HANATOUR EUROPE LTD | New Malden, | A rating |
| Hancroft Developers Private Limited | London | A rating |
| Handelsbanken plc | London | A rating |
| Handmade Cake Co Ltd | Maidenhead | A rating |
| Handshake International UK Limited | London | A rating |
| HANGAR 13 UK LIMITED | BRIGHTON | A rating |
| Hankook Tyre UK Limited | Daventry | A rating |
| HANKYU HANSHIN EXPRESS UK LIMITED | FELTHAM | A rating |
| Hankyu Travel International Europe UK Ltd | London | A rating |
| Hannover Services (UK) Limited | London | A rating |
| Hanns-Seidel-Stiftung UK Ltd | London | A rating |
| Hanover Communications | London | A rating |
| Hanover Investors Management LLP | London | A rating |
| Hansen Corporation Europe Ltd | London | A rating |
| Hansen Technologies CDE Limited | London | A rating |
| HANSHOW UK CO., LTD | London | A rating |
| Hanson Asset Management Limited | London | A rating |
| HANSON QUARRY PRODUCTS EUROPE LIMITED | Maidenhead | A rating |
| Hantec Markets Limited | London | A rating |
| Hanwa UK Limited | London | A rating |
| HANWHA OCEAN CO., LTD. | London | A rating |
| Hanwha Ocean Europe | London | A rating |
| Hanwha Vision Europe Limited | Chertsey | A rating |
| Haowei Property Limited | Manchester | A rating |
| Hapimag Management (UK) Ltd | London | A rating |
| Happiest Minds Technologies Pvt Ltd | Reading | A rating |
| HAPPYHARRY LTD | Sheffeld | A rating |
| Hara Global Capital Limited | London | A rating |
| Harada Industries (Europe) Limited | Birmingham | A rating |
| Harbert Management Corporation (Europe) LLC | London | A rating |
| Harbor Global UK Professional Services Ltd | London | A rating |
| Harbour Energy Plc | London | A rating |
| Harbour Energy Services Limited | London | A rating |
| HarbourVest Partners (UK) Limited | London | A rating |
| Harding Brothers Retail Limited | Bristol | A rating |
| Harding Loevner (UK) Ltd. | London | A rating |
| Hare & Humphreys Ltd | LONDON | A rating |
| Hargreaves Lansdown plc | Bristol | A rating |
| Harima UK Ltd | Hamel Hempstead | A rating |
| Harlaxton College | Grantham | A rating |
| Harley-Davidson Europe Ltd | Abingdon | A rating |
| Harman International Industries Limited | Hemel Hempstead | A rating |
| Harmonic (UK) Ltd. | Farnborough | A rating |
| Harmonic Consulting Services UK Limited | London | A rating |
| Harmony New Energy Auto Service (London) Ltd | London | A rating |
| Harness Group UK Limited | London | A rating |
| Harney Westwood & Riegels LLP | London | A rating |
| HarperCollins Publishers Limited | Glasgow | A rating |
| Harris Systems Limited | Wokingham | A rating |
| Harris Williams & Co. Limited | London | A rating |
| Harrison Street Real Estate Capital Ltd. | London | A rating |
| Harrison/Parrott Ltd | LONDON | A rating |
| Harsco Metals Group Limited | London | A rating |
| Hartford Underwriting Agency Ltd | London | A rating |
| Hartree Partners (UK) Limited | London | A rating |
| Harvey AI UK Ltd | Cheltenham | A rating |
| Harvey Nash Limited | London | A rating |
| Hasbro European Services | Uxbridge | A rating |
| HASEKO UK Limited | London | A rating |
| Haskoning UK Ltd | Peterborough | A rating |
| Hasselblad (UK) Limited | London | A rating |
| HASSELL | London | A rating |
| Hasta La Visa, Baby Limited | Barnet | A rating |
| Hastens Beds UK Limited | Milton Keynes | A rating |
| HATCH ASSOCIATES LIMITED | London | A rating |
| Hausfeld & Co LLP | London | A rating |
| Havanatour UK Limited | Potters Bar | A rating |
| Havas helia | London | A rating |
| Havas Media Limited | London | A rating |
| Havas Worldwide London | London | A rating |
| Haver Analytics Limited | London | A rating |
| Havin Bank Limited | London | A rating |
| Hawkes Bay Meat Co. (UK) Ltd T/A Ovation New Zealand (UK) | Bristol | A rating |
| Haworth U.K., LLC | London | A rating |
| Hay Technology Limited | London | A rating |
| HAYATO INTERNATIONAL UK LTD | London | A rating |
| Hayfin Capital Management LLP | London | A rating |
| Haygrove Limited | LEDBURY | A rating |
| Haylex Limited | Tonbridge | A rating |
| Haynes and Boone CDG LLP | London | A rating |
| Hays PLC | London | A rating |
| Hayward Tyler Limited | Luton | A rating |
| Haz International Limited | Hatfield | A rating |
| Hazelcast UK Limited | London | A rating |
| Hazeltree Treasury UK Ltd | London | A rating |
| Hazen and Sawyer UK Ltd | Nutley | A rating |
| HBA International | London | A rating |
| HBK Europe Management LLP | London | A rating |
| HBL Bank UK Limited | London | A rating |
| HBVB | Peterborough | A rating |
| HCA International Ltd | London | A rating |
| HCC Service Company Inc | London | A rating |
| HCD Economics limited | Knutsford | A rating |
| HCL Technologies UK Limited | London | A rating |
| HCN UK Management Services Limited T/a Welltower | London | A rating |
| HD Hyundai Electric UK | London | A rating |
| HD Hyundai Heavy Industries Co., Ltd | London | A rating |
| HD KOREA SHIPBUILDING & OFFSHORE ENGINEERING CO., LTD | London | A rating |
| HDI GLOBAL SE - UK BRANCH | London | A rating |
| HDR Consulting Limited | London | A rating |
| HE Space Operations Limited | Didcot | A rating |
| Headlands Tech UK Limited | London | A rating |
| Headline (England) LLP | London | A rating |
| Headspace Meditation Limited | London | A rating |
| Headspring Ltd. | London | A rating |
| Headstrong (UK) LTD | London | A rating |
| Healix International Limited | Esher | A rating |
| HealthHQ Group Limited | Worcester | A rating |
| HEALTHTAB LTD | MANCHESTER | A rating |
| Healthy.io (UK) Ltd | London | A rating |
| HeartFlow U.K. Ltd. | London | A rating |
| Heartflow UK Limited | London | A rating |
| HEAT AND CONTROL PTY LTD | LIVINGSTON | A rating |
| Heathrow Airport Holdings Ltd | Hounslow | A rating |
| Heavy Haul Rail Group Limited | Birmingham | A rating |
| Hebbia UK Limited | London | A rating |
| Hedosophia Services Limited | London | A rating |
| Heerema Marine Contractors UK Ltd | London | A rating |
| Heidi Health Ltd | London | A rating |
| Heidrick & Struggles (UK) Ltd | London | A rating |
| Heimstaden Group UK Ltd | London | A rating |
| Heineken UK Limited | Edinburgh | A rating |
| Heitman Financial UK LLC | London | A rating |
| HELI & POWER LIMITED | London | A rating |
| Helikon Investments Limited | London | A rating |
| Helio Consulting Ltd | Oxford | A rating |
| Helios Towers Group LLP | London | A rating |
| HellermannTyton | Wythenshawe | A rating |
| Hellman & Friedman LLP | London | A rating |
| Hellmann Worldwide Logistics Limited | Burton Upon Trent | A rating |
| Hello AI Limited | London | A rating |
| Helly Hansen UK Limited | Nottingham | A rating |
| Helm 360 Ltd | Bristol | A rating |
| HelpAge International | London | A rating |
| Helsing Limited | London | A rating |
| Hematogenix Laboratory Services Limited | Cheadle | A rating |
| Hengeler Mueller Partnerschaft von Rechtsanwaelten mbB | London | A rating |
| Hengst Filtration UK Limited | Morecambe | A rating |
| Henkel Ltd | Hemel Hempstead | A rating |
| Henry Bath & Son Ltd | Liverpool | A rating |
| HENRY SCHEIN ONE UK LIMITED | Gillingham | A rating |
| Henry Schein UK Holdings Limited | Gillingham | A rating |
| Hensel Recycling (UK) Ltd | Slinfold | A rating |
| Heraeus Conamic UK Ltd | Wallsend | A rating |
| Heraeus Electro-Nite (UK) Ltd | Chesterfield | A rating |
| Herbalife Europe Limited | Middlesex | A rating |
| Herbert Engineering Europe (UK) Ltd. | Glasgow | A rating |
| Herbert Smith Freehills Kramer LLP | London | A rating |
| Herbosch-Kiere Marine Contractors Ltd | Chiswick | A rating |
| Hercules Enterprises LTD | Southampton | A rating |
| Here Enterprise Limited | London | A rating |
| Heritage Auctions UK ltd | London | A rating |
| Herjavec Group Limited | Reading | A rating |
| Herman Miller Limited | Melksham | A rating |
| Herrenknecht International Ltd | Sunderland | A rating |
| Hershey UK Finance Limited | LONDON | A rating |
| Hertz Europe Limited | Uxbridge | A rating |
| HEURISTIX DIGITAL TECHNOLOGIES (UK) LIMITED | Ilford | A rating |
| Hewlett Packard Limited | Winnersh Triangle | A rating |
| Hexagon Metrology Ltd | TELFORD | A rating |
| HEXAWARE TECHNOLOGIES UK LTD | LONDON | A rating |
| Hexcel Composites Ltd | Duxford | A rating |
| HF Limited | Salford Quays | A rating |
| HG Capital LLP | London | A rating |
| HG Comms Ltd | Loughborough | A rating |
| HGC Global Communications (UK) Limited | London | A rating |
| HGG Construction | Sevenoaks | A rating |
| HH Associates Ltd | London | A rating |