| Cipher Holdings Limited | Cardiff | 2019 |
| Cipher Hunt Ltd | Bristol | 2007 |
| Cipher Midco Limited | London | 2025 |
| Cipher Opco Limited | London | 2025 |
| Cipher Risk Limited | London | 2018 |
| Cipher Stream Limited | Surbiton | 2009 |
| Cipher Topco Limited | London | 2025 |
| CIPHER26 Bidco Limited | London | 2026 |
| CIPHER26 Holdco Limited | London | 2026 |
| CIPHER26 Midco Limited | London | 2026 |
| Cipherid Holdings Limited | Barnsley | 2017 |
| Ciphertek Group Ltd | London | 2026 |
| Ciprianb Limited | Watford | 2025 |
| Cips 2025 Limited | Taunton | 2025 |
| Ciqala Limited | Streatham | 2011 |
| Cira Holdings Ltd | Portsmouth | 2024 |
| Circa Lifestyle Limited | Skipton | 2023 |
| CIRCA5000 Ltd | London | 2018 |
| Circacoin Ltd. | London | 2025 |
| Circadian Capital Limited | Belfast | 2011 |
| Circadian Commercial Finance Limited | Campbell Road | 2025 |
| Circadian FX Ltd | Bishop'S Stortford | 2017 |
| Circe the Company Ltd | London | 2025 |
| Circit UK Limited | Kingston Upon Thames | 2021 |
| Circle 1991 Limited | Coventry | 2020 |
| Circle Anglia Social Housing 2 PLC | London | 2015 |
| Circle Anglia Social Housing PLC | London | 2007 |
| Circle Bidco Limited | Bristol | 2021 |
| Circle Construct Group Ltd | Bristol | 2025 |
| Circle E Limited | Watford | 2022 |
| Circle Financial Services Limited | West Midlands | 1998 |
| Circle Funder 2 PLC | London | 2020 |
| Circle Funder 4 Limited | London | 2020 |
| Circle Insurance Services Limited | West Midlands | 1991 |
| Circle International Limited | London | 2004 |
| Circle Investco Limited | London | 2024 |
| Circle Lending Limited | London | 2016 |
| Circle Loans Limited | Oldham | 2002 |
| Circle Midco 1 Limited | Bristol | 2021 |
| Circle Midco 2 Limited | Bristol | 2021 |
| Circle Mortgages (UK) Limited | Maidstone | 2006 |
| Circle One Surf Ltd | Newton Abbot | 2023 |
| Circle Property Partnership Holdings Limited | London | 2019 |
| Circle Squared Capital Ltd | London | 2015 |
| Circle Systems Limited | Manchester | 2023 |
| Circle Topco Limited | Bristol | 2021 |
| Circle Trade Europe Ltd | London | 2018 |
| Circle UK Trading Limited | London | 2015 |
| Circlebox Holdings Limited | Glasgow | 2019 |
| Circled Square Risk Ltd | London | 2026 |
| Circlerock ME SPV Limited | London | 2023 |
| CIRCLO3 Limited | London | 2019 |
| Circo Consulting Ltd | Kilmarnock | 2020 |
| Circolo Holdings Ltd | London | 2026 |
| Circtec Ltd. | London | 2018 |
| Circuit 78 Holdings Limited | Nottingham | 2025 |
| Circuit 78 Investments Limited | Nottingham | 2026 |
| Circuit Group Limited | Portsmouth | 2007 |
| Circuit Holdco Limited | London | 2026 |
| Circuit Solutions Holdings Limited | Huntingdon | 2020 |
| CIRCUL8 INK Ltd | Oldham | 2021 |
| Circular Data Solutions Holdings Limited | Belfast | 2022 |
| Circular Economy Ltd | Coventry | 2013 |
| Circular Economy Market Ltd | London | 2025 |
| Circular Group Holdings Ltd | Magharafelt | 2023 |
| Circular Homes and Investments Limited | London | 2019 |
| Circular Investments Limited | Sutton | 2025 |
| Circular Property Holdings Limited | Leicester | 2024 |
| Circular Ventures Holdings Ltd | Weston-Super-Mare | 2025 |
| Circularclean-Wave.Org Ltd | London | 2021 |
| Circularcrowd Ltd | London | 2018 |
| Circularity BC Limited | London | 2022 |
| Circularity Capital (UK) Limited | London | 2014 |
| Circularity First Group Ltd | Weybridge | 2020 |
| Circularity Packaging One Limited | London | 2020 |
| Circulate Capital UK Limited | Milton Park | 2024 |
| Circulus Group Limited | Birmingham | 2021 |
| Circulus Holdco Limited | Birmingham | 2020 |
| Circumference Investments (Europe) Limited | London | 2016 |
| Circumventures | London | 2018 |
| Circus Healthcare Limited | Truro | 2025 |
| Cirelle Associates Limited | Grays | 2002 |
| Cirencester Friendly Membership Rewards Limited | Cirencester | 2017 |
| Cirencester Ltd | Cirencester | 2024 |
| Cirencester Mortgage Co Limited | Cirencester | 2015 |
| Cirex Holdings Ltd | Stockport | 2023 |
| Ciriello Fennell Holdings Ltd | Bath | 2022 |
| Cirion Technologies Holding I Limited | London | 2007 |
| Cirion Technologies Holding II Limited | London | 2007 |
| Cirka Services Holdings Limited | London | 2022 |
| Cirkus International Limited | London | 2014 |
| Cirmhor Properties UK Limited | Broadway | 2023 |
| Cirqlr East Limited | London | 2024 |
| Cirqlr Group Finco Limited | London | 2023 |
| Cirqlr Group Limited | London | 2023 |
| Cirqlr London Limited | London | 2024 |
| Cirqlr Serviceco Limited | London | 2025 |
| Cirrata V UK Limited | London | 2024 |
| Cirrostratus 1 Limited | Glossop | 2023 |
| Cirrostratus 2 Limited | Derbyshire | 2023 |