| Cirrus Furniture Ltd | Rossendale | 2024 |
| Cirrus Laser Limited | Burgess Hill | 1987 |
| Cirrus Limited | Craigavon | 1987 |
| Cirrus Logic International (UK) Ltd | Edinburgh | 1984 |
| Cirrus Plastics Limited | Carn Industrial Estate | 1992 |
| Cirrus Research PLC | Hunmanby | 1970 |
| Cirruz Ltd | Oxford | 2019 |
| Cirstoiu Ltd | Birmingham | 2025 |
| Cirteq Limited | Keighley | 1995 |
| CIS (Northampton) Limited | Kettering | 2004 |
| CIS Associates Ltd | Coleford | 2013 |
| CIS Street Furniture Limited | Ascot | 1995 |
| Ciscar Export UK Ltd | Chatham | 2021 |
| Cispex Limited | Cardiff | 2020 |
| Cissores Limited | Bromley | 2021 |
| Cissy Green Limited | Lancashire | 2003 |
| Cistermiser Limited | Leeds | 1979 |
| CIT Technology Limited | Mitcham | 2002 |
| Cita Furniture Ltd | Strabane | 2008 |
| Cita Lighting Ltd | Glasgow | 2023 |
| Citadel Analytics (UK) Ltd. | London | 2018 |
| Citadel Brewing Ltd | London | 2025 |
| Citadel Conservation & Restoration Ltd | Martock | 2021 |
| Citadel Joinery Limited | Welshpool | 2024 |
| Citadel Miniatures Limited | Nottingham | 1978 |
| Citadel Products Limited | Wimborne | 1970 |
| Citadel Services Ltd | Brierley Hill | 2015 |
| Citadel Spark Erosion Limited | Dartford | 2005 |
| Citadel Window Ltd | London | 2025 |
| Citaglen (Signs) Ltd | Westbury | 1982 |
| Citech Energy Recovery Solutions (UK) Ltd | Hessle | 2013 |
| Citek Ltd | Liskeard | 2025 |
| Citibat UK Limited | Reigate | 2020 |
| Citibloks Limited | Stalybridge | 2011 |
| Cities Nutrition Limited | Burnley | 2026 |
| Citiprint (London) Ltd | London | 2025 |
| Citiprint Ltd | Grimsby | 2016 |
| Citix UK Ltd | London | 2023 |
| Citizen Blades Ltd | London | 2024 |
| Citizen Concern Limited | Hayes | 2024 |
| Citizen Spritz Limited | Newbury | 2021 |
| Citizen Watch United Kingdom, Ltd | Wokingham | 2000 |
| Citradi Ltd | Charlbury | 2017 |
| Citrinava Ltd | Edgware | 2019 |
| Citrine Marine Services Ltd | South Croydon | 2026 |
| Citrosoft Drinks Limited | Burnley | 1987 |
| Citrus Creative UK Limited | Lytham St Annes | 2018 |
| Citrus Design & Print Limited | Swindon | 2006 |
| Citrus Seating Ltd | Cheltenham | 2014 |
| City & Co Contractors Limited | London | 2020 |
| City & County Graphics Limited | Abingdon | 2009 |
| City & County Refrigeration and Air Conditioning Limited | Witney | 2018 |
| City Air Conditioning Ltd | Rochester | 2017 |
| City Aluminium Ltd | Birmingham | 2024 |
| City Aluminium Shopfronts NW Limited | Oldham | 2017 |
| City Bikes Limited | Liverpool | 2026 |
| City Blinds & Shutters Ltd | Dundee | 2025 |
| City Blinds Limited | Ballyclare | 1986 |
| City BMS Limited | Ashtead | 2014 |
| City Building and Joinery Limited | Houghton Le Spring | 2020 |
| City Cakes Company Limited | London | 1992 |
| City Centre Sign & Print Ltd | Hull | 2021 |
| City Ceramics Dental LAB Edinburgh Ltd | Glasgow | 2021 |
| City Ceramics Dental Laboratory Limited | Newquay | 2008 |
| City Commuter Limited | London | 2016 |
| City Company Seals Limited | Wickford | 1973 |
| City Compressor Services Ltd. | Bellshill | 2010 |
| City Computing Trading Limited | Guildford | 2013 |
| City Concrete Ltd | Bilston | 2024 |
| City Cooling Limited | Blackpool | 2004 |
| City Copy Centre Limited | Woodford Green | 1994 |
| City Crafts Limited | Edinburgh | 2000 |
| City Dental LAB Limited | Basingstoke | 2016 |
| City Dental Laboratory (Swansea) Limited | | 2003 |
| City Desk Recycling and Removals Ltd | Leicester | 2010 |
| City Display Limited | Hemel Hempstead | 2011 |
| City Electric Vehicles Ltd | London | 2022 |
| City Electrical Group Limited | Rochester | 2025 |
| City Energies UK Ltd | Newport | 2000 |
| City Engineering Limited | London | 1986 |
| City Espresso Limited | London | 2017 |
| City Export Packers Limited | Newport | 2004 |
| City Fabric Finishers Limited | Leicester | 1994 |
| City Facilities Ltd | Rochester | 2023 |
| City Farm Technologies Limited | High Wycombe | 2013 |
| City Fire Protection Limited | Gloucester | 2003 |
| City Fire Surrounds Limited | Newcastle Upon Tyne | 2003 |
| City Forge Limited | Halesowen | 1954 |
| City Forklift Trucks Limited | Skipton | 2001 |
| City Fuel Services (Manchester) Limited | Old Harlow | 2015 |
| City Fuel Services Limited | Old Harlow | 2015 |
| City Furniture Ltd | Rotherham | 2023 |
| City Games Limited | London | 1999 |
| City Glass UK Limited | Edinburgh | 2003 |
| City Glass(Manchester)Co. Limited | Manchester | 1999 |
| City Goddess Limited | Romford | 2003 |
| City Hydraulics Ltd | Worcester | 2006 |
| City Irrigation Limited | Bromley | 1986 |
| City Lift Services (North West) Limited | Runcorn | 2005 |
| City Light Services Ltd | Rochester | 2023 |