| Clock House Court Management Company Limited | Real estate | 1999 |
| CLS Business & Development Ltd | Administrative & support | 2011 |
| CLS Business Support Limited | Administrative & support | 2019 |
| CLS Corporation Limited | Administrative & support | 2013 |
| Club '76 Ltd | Wholesale & retail | 2019 |
| CM Power Generation Limited | Professional & scientific | 2025 |
| Coached by Lemon Ltd | Other services | 2022 |
| Colborough Limited | Professional & scientific | 2008 |
| Colbro Properties Limited | Households | 2015 |
| Cole & Co Media Ltd | Professional & scientific | 2026 |
| Coledream Residents Company Limited | Households | 1987 |
| Coleman Stone Ltd | Construction | 2023 |
| Colin Easson (Motors) Limited | Wholesale & retail | 1976 |
| Colton & Hollis Properties Ltd | Real estate | 2021 |
| Come & Play Education Ltd | Arts & recreation | 2025 |
| Commercial Fit-Out Services Ltd | Construction | 2017 |
| Commodities Trading (UK) Developments Limited | Administrative & support | 2011 |
| Commodities Trading (UK) Limited | Wholesale & retail | 2011 |
| Compton Energy Associates Ltd | Professional & scientific | 2018 |
| Conen Limited | Hospitality | 2017 |
| Conlon & Leach Limited | Information & communication | 2013 |
| Connolly Financial Planning Ltd | Professional & scientific | 2024 |
| Conservation Architecture Ltd | Professional & scientific | 2023 |
| Constantine Creative Limited | Real estate | 2019 |
| Construction Interior Design Limited | Construction | 1992 |
| Consult Select Ltd. | Professional & scientific | 2014 |
| Cool Bedroom Ltd | Construction | 2026 |
| Coping Stones UK Limited | Manufacturing | 2015 |
| Coppice Homes (Rutland) Ltd | Construction | 2013 |
| Corbyde Properties Limited | Real estate | 2024 |
| Cornerhouse Retreats Limited | Real estate | 2025 |
| Cornerstone Nominees Limited | Professional & scientific | 2004 |
| Cornerstone Nominees North Limited | Administrative & support | 2007 |
| Cornerstone Nominees South Limited | Administrative & support | 2007 |
| Coronation Retreats Limited | Real estate | 2024 |
| Corpselight Games Ltd | Information & communication | 2025 |
| Cosmo Experts Ltd | Professional & scientific | 2024 |
| Cottesmore Owners Management Company Limited | Real estate | 2004 |
| Counselling BEE Limited | Health & social care | 2022 |
| Countryside Masonry Limited | Construction | 2017 |
| Cover Price Advice Limited | Administrative & support | 2014 |
| Cowgirl Like ME Ltd | Professional & scientific | 2024 |
| COX & Key LLP | | 2016 |
| COX Commercial Investments Ltd | Financial services | 2015 |
| COX Property Ltd | Real estate | 2014 |
| Cranswick Consulting Limited | Professional & scientific | 2025 |
| Creasey Enterprises Limited | Agriculture & fishing | 2020 |
| Creative Minds Rutland Ltd | Health & social care | 2023 |
| Creative Work Builders Ltd | Construction | 2022 |
| Creme Hair and Beauty Treatments Ltd | Other services | 2011 |
| Crescera Commerce Ltd | Wholesale & retail | 2025 |
| Crewyard Construction Company Ltd | Construction | 2012 |
| Cricket Pavilion Ltd | Wholesale & retail | 2022 |
| Croft Medical Imaging Limited | Health & social care | 1995 |
| Cromwells Menswear Limited | Wholesale & retail | 2023 |
| Crown & Dial Jewellers Limited | Wholesale & retail | 2025 |
| Cryptogreen Ltd | Financial services | 2021 |
| Cube-Intermediary Ltd | Financial services | 2013 |
| Cubic Technologies Ltd | Information & communication | 2002 |
| Cult Motorcycles Ltd | Wholesale & retail | 2018 |
| Curated Spaces Ltd | Professional & scientific | 2026 |
| Curlew Land Limited | Agriculture & fishing | 2025 |
| Current Node Ltd | Information & communication | 2025 |
| Cutest Consumer Research LLP | | 2019 |
| CYO Limited | Administrative & support | 2010 |
| D & a Music Limited | Arts & recreation | 2007 |
| D and J Underwood Limited | Wholesale & retail | 2011 |
| D Burgin Limited | Professional & scientific | 2007 |
| D E Cliffe Plumbing & Heating Ltd | Construction | 2025 |
| D Hope Ltd | Professional & scientific | 2010 |
| D. Coburn Limited | Financial services | 2025 |
| DA Supplies Ltd | Professional & scientific | 2020 |
| DAB TV and Content Ltd | Information & communication | 2020 |
| Dads Holidays Limited | Hospitality | 2018 |
| Daniel Stanton Ltd | Transport & logistics | 2022 |
| Dare to Think Limited | Professional & scientific | 2013 |
| Darlton Hall Estates Ltd | Real estate | 2013 |
| Darn Knit Ltd. | Wholesale & retail | 2018 |
| David Michael Taylor (Exton) Limited | Real estate | 2014 |
| David Miller Homes Limited | Real estate | 2011 |
| DB Freezer Services Limited | Manufacturing | 2015 |
| Ddse Ltd | Arts & recreation | 2016 |
| Deanscroft Ltd | Real estate | 2020 |
| Debenham Advisory Ltd | Professional & scientific | 2026 |
| Deco ID Ltd | Professional & scientific | 2023 |
| Deliverance County Wholesale Ltd | Manufacturing | 2025 |
| Denton Seismo Ltd | Professional & scientific | 2019 |
| Desi Boys PUB Company Ltd | Hospitality | 2025 |
| Desk & Company Coworking Ltd | Real estate | 2022 |
| Detail 42 Limited | Professional & scientific | 2017 |
| Develop Oakham Limited | Information & communication | 2019 |
| Dexter Developments and Property Ltd | Construction | 2025 |
| Diamond Drill Ltd | Health & social care | 2022 |
| Direct Cosmetics Limited | Wholesale & retail | 1977 |
| Dive Rutland Limited | Arts & recreation | 2015 |
| Diverse Rope Access Ltd | Manufacturing | 2021 |
| Divorce Mediation Resolution Limited | Other services | 2020 |
| DJB Music Ltd | Administrative & support | 2008 |
| DJM Video Production Ltd | Information & communication | 2023 |
| DJR Claims Services Ltd | Construction | 2020 |