| Hyundai Marine & Fire Insurance | London | A rating |
| Hyundai Motor UK Ltd | Leatherhead | A rating |
| Hyundai Oilbank Co., Ltd. London Branch | London | A rating |
| Hyve International Events Limited | London | A rating |
| I -Exceed Technology Solutions Limited | Halesowen | A rating |
| I Squared Capital Advisors (UK) LLP | London | A rating |
| I-care Reliability UK Limited | St Albans | A rating |
| I-TELERAD UK Limited | London | A rating |
| I.D.T.-Systems Ltd | FARNHAM | A rating |
| I.F.P. Forest and Paper Products (UK) Limited | Newbury | A rating |
| I2Global Ltd | Oldham | A rating |
| i6 Systems Limited | Farnborough | A rating |
| IA U.K. | LONDON | A rating |
| IAG Limited | Huntingdon | A rating |
| ib vogt UK Ltd | London | A rating |
| IBA Group Ltd | Leatherhead | A rating |
| IBC TV Ltd. | Hmamersmith | A rating |
| IBC Vehicles Limited | Luton | A rating |
| IBERICA DE COMPRAS CORPORATIVAS SL | MILTON KEYNES | A rating |
| IBISWorld Ltd | London | A rating |
| IBM UK Ltd | Winchester | A rating |
| IBS Software Europe Ltd | Bracknell | A rating |
| iC Consult UK Limited | London | A rating |
| ICBC (London) plc | London | A rating |
| ICBC Standard Bank PLC | London | A rating |
| ICE Data Services Europe Limited | London | A rating |
| ICE MARKETS LTD | london | A rating |
| Icertis Group Limited | London | A rating |
| ICF Consulting Services Limited | London | A rating |
| ICG Medical Limited | London | A rating |
| ICG PLC | London | A rating |
| Ichibanya UK Ltd | London | A rating |
| ICICI Bank UK PLC | London | A rating |
| ICM Advisers Limited | London | A rating |
| Icomera UK Limited | Chatham | A rating |
| Icon Books Ltd | London | A rating |
| iCON Infrastructure LLP | London | A rating |
| ICONIQ Capital (UK) Limited | London | A rating |
| iCOVER (Screening) Ltd | London | A rating |
| Icreon UK Ltd | London | A rating |
| iCrossing Limited | Brighton | A rating |
| ICU Medical International Limited | Ashford | A rating |
| ICW Group Holdings Ltd | Belfast | A rating |
| ID Logistics Services UK Ltd | Milton Keynes | A rating |
| ID MEDICAL GROUP LIMITED | WOLVERTON MILL SOUTH | A rating |
| IDC UK Limited | London | A rating |
| Ideal Standard (UK) Ltd | Hull | A rating |
| Ideapharma Ltd | London | A rating |
| IDEMIA UK Ltd | Tewkesbury | A rating |
| IDEO LLC | London | A rating |
| IDEO LP | London | A rating |
| IDEXX Laboratories | Wetherby | A rating |
| IDIADA Automotive Technology UK Ltd | Nuneaton | A rating |
| IDIS EUROPE LTD | BRENTFORD | A rating |
| IDOM (UK) LTD | London | A rating |
| IDP Connect Ltd | London | A rating |
| Idverde Limited | Coventry | A rating |
| Idx Corporation London Ltd | Swindon | A rating |
| IES London | London | A rating |
| Ieso Digital Health Limited | Cambridge | A rating |
| Ifchor Galbraiths UK Limited | London | A rating |
| IFCO SYSTEMS UK LTD | PRINCES RISBOROUGH | A rating |
| IFIMI Limited | London | A rating |
| IFM Investors (UK) Ltd | London | A rating |
| IFPI Secretariat | London | A rating |
| IFSA UK LIMITED | LONDON | A rating |
| IG Design Group PLC | Newport Pagnell | A rating |
| IG Group Holdings plc | London | A rating |
| IG Metal Recycling Limited | Newark | A rating |
| IG Renewables Limited | London | A rating |
| iGenie Limited | Isleworth | A rating |
| Iglu Network Ltd. | London | A rating |
| Ignis Energy UK Ltd | Liverpool | A rating |
| Ignition Wealth UK Limited | London | A rating |
| IGT Solutions Private Limited | London | A rating |
| igus UK Limited | Northampton | A rating |
| iGuzzini illuminazione U.K. Limited | Guildford | A rating |
| IGX Global Limited | London | A rating |
| IHI Europe Ltd. | London | A rating |
| IHS Africa (UK) Limited | Surrey | A rating |
| Ihsan International Limited | Greater London | A rating |
| IIJ Europe Limited | London | A rating |
| Iino UK Limited | London | A rating |
| IKEA Ltd. | London | A rating |
| Ikiru People Limited | Basingstoke | A rating |
| Ikon Science Limited | Surbiton | A rating |
| IKRA UK LTD | Ashford | A rating |
| Il Makiage GB Ltd | London | A rating |
| ILJIN ELECTRIC UK | Surrey | A rating |
| Illumina Cambridge Limited | Great Abington | A rating |
| Illumio UK Limited | Reading | A rating |
| Illycaffe UK Limited | Northampton | A rating |
| iM Global Partner UK | London | A rating |
| Image Frame Investment (UK) Limited | London | A rating |
| Imagedata (trading division of ITW Limited) | Essex | A rating |
| Imagination Technologies Limited | Kings Langley | A rating |
| Imagine Communications EMEA (UK) Limited | Surrey | A rating |
| Imagine Software (UK), Ltd. | London | A rating |
| iMaker Group Limited | London | A rating |
| iManage EMEA Limited | London | A rating |
| IMD Media Limited | London | A rating |
| IMD Technologies Ltd | London | A rating |
| IMEC Cambridge UK Limited | Cambridge | A rating |
| Imerys Minerals Ltd | St Austell | A rating |
| IMES Engineering & Contracting Ltd | Stafford | A rating |
| IMG Media Limited | London | A rating |
| IMI Plc | Birmingham | A rating |
| IMILE LOGISTICS CO., LTD | Hounslow | A rating |
| Immediate Media Company Limited | London | A rating |
| Immunodiagnostic Systems Holdings Limited | Boldon | A rating |
| Immuta Limited | Reading | A rating |
| Impact IT Solutions (UK) Ltd | BRISTOL | A rating |
| Impact Radius Ltd | London | A rating |
| Impax Asset Management Group plc | London | A rating |
| Imperial Capital (International) LLP | London | A rating |
| Imperial Chemical Industries Limited (Trading as ICI Paints AkzoNobel) | Slough | A rating |
| Imperial Tobacco Ltd | Bristol | A rating |
| Imply Data UK Limited | London | A rating |
| Improbable Worlds Ltd | London | A rating |
| Imtech Engineering Services London & South Ltd | Nottingham | A rating |
| IMV Europe Limited | Shepreth, Royston | A rating |
| In-Part Publishing Ltd | Sheffield | A rating |
| In-Situ Europe Ltd | Redditch | A rating |
| In-tech Group Ltd | Warwick | A rating |
| Inatech Europe Ltd | London | A rating |
| Inbrit Logistics Limited | Park Royal | A rating |
| Inchcape Management (Services) Limited | London | A rating |
| InCloudCounsel Limited | London | A rating |
| InContext Solutions Limited | London | A rating |
| Incopro Limited | London | A rating |
| INCTURE TECHNOLOGY LIMITED | Harrow | A rating |
| IncubEx Limited | London | A rating |
| Indaver Rivenhall Limited | Harlow | A rating |
| Indeed UK Operations Limited | London | A rating |
| Indegene Healthcare UK Ltd | London | A rating |
| Independent Project Analysis | Reading | A rating |
| Independent Technology Systems Limited | Bristol | A rating |
| Index Exchange Limited | London | A rating |
| Index Ventures (UK) LLP | London | A rating |
| India Eateries Limited | London | A rating |
| INDIA INFRASTRUCTURE FINANCE COMPANY (UK) LIMITED | LONDON | A rating |
| IndiaCast UK Ltd | Harrow | A rating |
| INDIAN REGISTER OF SHIPPING | London | A rating |
| Indigo Consulting London Limited | London | A rating |
| Indivior UK Limited | Slough | A rating |
| Indochine International UK Limited | London | A rating |
| Indometal (London) Limited | London | A rating |
| Indra Sistemas S.A. | Whiteley | A rating |
| Induction Healthcare (UK) Limited | London | A rating |
| IndusInd Bank Limited | London | A rating |
| Industrial & Financial Systems, IFS UK Ltd | Staines-upon-Thames | A rating |
| Industrial Bank of Korea | London | A rating |
| Industrial Design Consultancy Ltd | Datchet | A rating |
| INDUSTRIAL DIELECTRICS UK LTD T/A IDI COMPOSITES INTERNATIONAL | OLDBURY | A rating |
| INDUSTRIAL LIGHT & MAGIC UK LIMITED | LONDON | A rating |
| Industrial Logic Europe LTD | London | A rating |
| Industrial Projects Services UK Limited | London | A rating |
| Industrial Welding Services Ltd | Chester | A rating |
| INECO U.K | East Grinstead | A rating |
| INELTRON SOLUTIONS UK LTD | London | A rating |
| Infarm Indoor Urban Farming UK LIMITED | London | A rating |
| Infineon Technologies UK Limited | Bristol | A rating |
| Infineum UK Ltd | Abingdon | A rating |
| Infinity Power Development UK Limited | London | A rating |
| Infios U.K. Ltd | Blackpool | A rating |
| Influencer Ltd | London | A rating |
| Infoblox UK Limited | London | A rating |
| Infoplus Technologies UK Limited | London | A rating |
| Infor (Midlands II) Limited | Shirley | A rating |
| Inforcer Ltd | Richmond | A rating |
| Informa UK Limited | London | A rating |
| Informatica Software Ltd | Maidenhead | A rating |
| Information Development Co., Ltd. London Branch | London | A rating |
| Information Security Media Group UK LTD | Windsor | A rating |
| Information Services Consulting Limited | Eastleigh | A rating |
| Information Services Group Europe Limited | Guildford | A rating |
| Informed Solutions Limited | Altrincham | A rating |
| Informetis Europe Ltd | Cambridge | A rating |
| Infosys Fluido UK LTD | London | A rating |
| Infosys Limited | London | A rating |
| InfoTrack Limited | London | A rating |
| Infovista Limited | Guildford | A rating |
| Infranity | London | A rating |
| InfraRed Partners LLP | London | A rating |
| Infrasecure Limited | London | A rating |
| Infrasoft Technologies Limited | London | A rating |
| InfraVia Partners UK Limited | London | A rating |
| Infuse Consulting Limited | Leicester | A rating |
| Infy Consulting Company Limited | London | A rating |
| ING Services Limited | London | A rating |
| Ingenico UK Ltd | Dalgety Bay | A rating |
| Ingenta UK Limited | Oxford | A rating |
| Ingeteam Ltd. | Portbury | A rating |
| Ingevity UK Ltd | Warrington | A rating |
| Ingram Micro (UK) Ltd | Milton Keynes | A rating |
| Ingredion UK Limited | Manchester | A rating |
| Inhabit Europe Ltd. | London | A rating |
| INHUS Limited | Leeds | A rating |
| Inizio Evoke Europe Limited | London | A rating |
| Inizio Services UK Limited | London | A rating |