| Charcoal Fulwell Ltd | Hospitality | 2025 |
| Chareth Ltd | Agriculture & fishing | 2018 |
| Charlie & Carter Ltd | Professional & scientific | 2024 |
| Charlie Robert IAN Scott Ltd | Professional & scientific | 2023 |
| Charlotte Cruddas Limited | Health & social care | 2021 |
| Charm Store Ltd | Wholesale & retail | 2025 |
| Chavtown Properties Ltd | Real estate | 2010 |
| Cheech and DR Cheech Limited | Administrative & support | 2021 |
| Cheeky Bears Events CIC | Administrative & support | 2026 |
| Cheeky Churro's Ltd | Hospitality | 2023 |
| Cheemas 2 Ltd | Arts & recreation | 2025 |
| Cheemas Sunderland Ltd | Arts & recreation | 2019 |
| Cheese and Tomato Ltd | Hospitality | 2025 |
| Cheese and Tomatoes Ltd | Hospitality | 2025 |
| Cheesy Pizza Ltd | Hospitality | 2025 |
| Chef Delight Easington Ltd | Hospitality | 2019 |
| Cherry Meadow Properties Ltd | Real estate | 2022 |
| Cherry&Stone Engineering Ltd | Professional & scientific | 2025 |
| Chester Barber NE Ltd | Other services | 2025 |
| Chester Fusion Ltd | Hospitality | 2024 |
| Chester Homes North West Limited | Construction | 2021 |
| Chester Road Halal Food Store Limited | Wholesale & retail | 2022 |
| Chesterphones Limited | Information & communication | 2019 |
| Chesters Tandoori Ltd | Hospitality | 2026 |
| Cheva Limited | Hospitality | 2021 |
| Chido Padel Limited | Wholesale & retail | 2025 |
| Chieftain Brooks Limited | Professional & scientific | 2011 |
| Chilled Milk Ltd | Wholesale & retail | 2015 |
| Chimora Properties Limited | Real estate | 2025 |
| China Express Sunderland Ltd | Hospitality | 2026 |
| Chinatool UK Limited | Wholesale & retail | 2004 |
| Chinese Harry Ltd | Hospitality | 2019 |
| Chinnys Signature Limited | Wholesale & retail | 2026 |
| Chipat Ltd | Administrative & support | 2024 |
| Chisholm Property Ltd | Real estate | 2019 |
| Chisholm Wind Services Ltd | Professional & scientific | 2026 |
| Choicity Limited | Real estate | 2023 |
| Chomchom Catering Ltd | Hospitality | 2024 |
| Chomchom Spice Sunderland Limited | Hospitality | 2019 |
| Chris Askew Services Ltd | Construction | 2019 |
| Chris Charlton (Kitchen Design) Limited | Wholesale & retail | 2009 |
| Chris Wilson Bookkeeping and Payroll Solutions Limited | Professional & scientific | 2025 |
| Chrisifyx Hub Ltd | Health & social care | 2022 |
| Chrissy's Bar Ltd | Hospitality | 2022 |
| Christian James Associates Ltd | Professional & scientific | 2015 |
| Christie Fabrication Limited | Manufacturing | 2025 |
| Christines Petals Ltd | Wholesale & retail | 2018 |
| Christopher Hill Fabrications Ltd | Manufacturing | 2026 |
| Chubscakes Limited | Manufacturing | 2024 |
| Chugo Logistics Limited | Wholesale & retail | 2026 |
| Chuze UP Ltd | Wholesale & retail | 2022 |
| Chymart Limited | Wholesale & retail | 2026 |
| Chyrich Limited | Public administration | 2022 |
| Cimex Service (UK) Limited | Construction | 1976 |
| Circle 25 Welfare Association UK Ltd | Education | 2025 |
| Circle Development Recruitment Limited | Administrative & support | 2017 |
| Circlesave Ltd | Information & communication | 2025 |
| Cirqle App Ltd | Information & communication | 2026 |
| Citizens Advice Sunderland | Other services | 2007 |
| City 2 City Utilities Ltd | Energy | 2025 |
| City Auctions Limited | Administrative & support | 2013 |
| City Auto Solutions Limited | Wholesale & retail | 2009 |
| City Blessed Apartments Limited | Real estate | 2021 |
| City Bridge Group Limited | Real estate | 2013 |
| City Bridge Serviced Apartments Limited | Real estate | 2016 |
| City Building Services (NE) Ltd | Construction | 2012 |
| City Dental (Dental Prosthetics) Limited | Health & social care | 2010 |
| City Estates and Developments Limited | Construction | 2019 |
| City Financial Solutions Limited | Professional & scientific | 2011 |
| City Hospitals Independent Commercial Enterprises Limited | Health & social care | 2013 |
| City Housing Group Limited | Households | 2023 |
| City Leasing (Holdings) Limited | Financial services | 2023 |
| City Leasing (Sunderland) Limited | Wholesale & retail | 1961 |
| City Market Sunderland Limited | Wholesale & retail | 2025 |
| City of Sunderland Amateur Swimming Club C.I.C. | Arts & recreation | 2011 |
| City Properties Development & Lettings Limited | Real estate | 1984 |
| City Slice Ltd | Hospitality | 2025 |
| City Store Sunderland Ltd | Wholesale & retail | 2018 |
| City Taxis (Sunderland) Limited | Transport & logistics | 2006 |
| City Wholesaler Ltd | Wholesale & retail | 2018 |
| Citymart Express Ltd | Wholesale & retail | 2026 |
| CJ Accountancy & Taxation Services Ltd | Professional & scientific | 2021 |
| CJ Listings Ltd | Wholesale & retail | 2024 |
| CJF Travels Renewables Services Limited | Energy | 2026 |
| Cjorco Ltd | Health & social care | 2025 |
| CJP Property Capital Ltd | Real estate | 2025 |
| CJS Investments Ltd | Real estate | 2023 |
| CK Contractors North East Ltd | Construction | 2024 |
| Ckcs Consultants Limited | Professional & scientific | 2007 |
| Ckml PAT Test Ltd | Other services | 2013 |
| CL Training (NE) Ltd | Other services | 2024 |
| Clacey's Ltd | Hospitality | 2018 |
| Cladd-Well Limited | Construction | 2025 |
| Clairebeautyshop Ltd | Other services | 2025 |
| Clal Piping Services Ltd | Professional & scientific | 2023 |
| Clara Power (Developments) Ltd | Energy | 2026 |
| Claremont Terrace Management Limited | Real estate | 2004 |
| Clarendon House (Darlington) Management Company Limited | Households | 2000 |
| Claretblew Energy Ltd | Manufacturing | 2020 |
| Clark Davison Consultancy Services Limited | Professional & scientific | 2024 |