| Concept Design Group Limited | Hospitality | 2021 |
| Concept-Mep Limited | Professional & scientific | 2020 |
| Conficio Recruitment Limited | Administrative & support | 2022 |
| Congee Limited | Construction | 2013 |
| Conley Consultancy Services Limited | Other services | 2025 |
| Connell Windows, Doors & Fascias Ltd | Construction | 2025 |
| Conquest Homes LLP | | 2005 |
| Consult GK Limited | Professional & scientific | 2022 |
| Consultancy 34 Limited | Administrative & support | 2018 |
| Content Technology Ltd | Administrative & support | 2024 |
| COOL4HIRE Limited | Administrative & support | 2022 |
| Coopernixon Corporate Communications Limited | Professional & scientific | 2011 |
| Copter CAM Limited | Professional & scientific | 2013 |
| Coral Insurance Services Limited | Financial services | 2013 |
| Corcullen Properties Limited | Real estate | 2024 |
| Corn Exchange Theatre Company | Arts & recreation | 2001 |
| Coulter Elite Resourcing Limited | Administrative & support | 2008 |
| Country Lounge Ltd | Hospitality | 2020 |
| Coverfwd Limited | Financial services | 2020 |
| Cpop TI Ltd | Information & communication | 2020 |
| Craig Compton Builders Limited | Construction | 2017 |
| Crash Rhino Ltd | Information & communication | 2024 |
| Crassula Developments Limited | Construction | 2019 |
| Crawford Music Ltd | Education | 2026 |
| Creative Design & Print (Stamford) Limited | Manufacturing | 2013 |
| CRF Couriers Ltd | Transport & logistics | 2024 |
| Crime Cure Group Limited | Construction | 2021 |
| Criminal Injury Limited | Professional & scientific | 2025 |
| Crimson Folia Ltd | Professional & scientific | 2019 |
| Critchford Consultancy Ltd | Professional & scientific | 2026 |
| Croft Commercial Developments Limited | Real estate | 1990 |
| Crossfit Oakham Limited | Arts & recreation | 2022 |
| Crow + OWL Limited | Real estate | 2025 |
| Crownfield Motors Services Ltd | Wholesale & retail | 2025 |
| Crox Limited | Professional & scientific | 2017 |
| CTD Construction Ltd | Administrative & support | 2017 |
| Culea Limited | Real estate | 2010 |
| Curatus Experiences Limited | Arts & recreation | 2025 |
| Current PV Ltd | Professional & scientific | 2026 |
| Curve Holdings Group Limited | Financial services | 2026 |
| Curve IP Limited | Administrative & support | 2026 |
| Custom Lawn Care Franchise Ltd | Administrative & support | 2018 |
| Custom Lawn Care Ltd | Administrative & support | 2007 |
| CWG Pension Trustee Limited | Financial services | 2019 |
| Cycleverse Ltd | Information & communication | 2026 |
| D F Coulam Limited | Manufacturing | 2012 |
| D Hicks Properties Ltd | Households | 2025 |
| D Squared Holdings Limited | Administrative & support | 2011 |
| D Squared Limited | Administrative & support | 2006 |
| D&H Creative Limited | Wholesale & retail | 2022 |
| D'Urban Communications Ltd | Professional & scientific | 2017 |
| D.J.Bryson MED Limited | Health & social care | 2023 |
| D.S Elliott & SON Limited | Real estate | 2018 |
| Daiomed Limited | Health & social care | 2025 |
| Danegeld Place Stamford Management Limited | Households | 2001 |
| Darcy Taylor Limited | Professional & scientific | 2025 |
| Datacode Limited | | 1983 |
| Datamaxis Ltd | Administrative & support | 2013 |
| Dave Brockbank Ltd | Construction | 2015 |
| Davenport-Simpson Consulting Limited | Professional & scientific | 2004 |
| David Corfield Communications Ltd | Arts & recreation | 2018 |
| David Evans Associates LLP | | 2010 |
| David Higgs Consulting Ltd | Professional & scientific | 2022 |
| David Meakin Developments Limited | Construction | 1981 |
| David Price Consultants Limited | Professional & scientific | 2023 |
| David Whitwell Ltd | Professional & scientific | 2016 |
| Davis and Birch Holdings Limited | Financial services | 2023 |
| Day's Accountancy Services Limited | Professional & scientific | 2011 |
| Ddgl (Falcon Way) Ltd | Construction | 2023 |
| Ddgl (Market Overton) Limited | Construction | 2023 |
| Ddgl (North Witham) Ltd | Construction | 2023 |
| Ddgl (South Witham) Ltd | Construction | 2023 |
| Ddgl (Titchmarsh) Ltd | Construction | 2024 |
| Ddgl Construction Limited | Construction | 2021 |
| DE Carpentry Ltd | Construction | 2016 |
| Deaton Developments Ltd | Real estate | 2021 |
| Deeping Consulting Ltd | Wholesale & retail | 2007 |
| Della SOL Ltd | Manufacturing | 2025 |
| Delta Bravo Property Services Ltd | Construction | 2022 |
| Desk Club Stamford Ltd | Real estate | 2019 |
| Destiny Pubs Ltd | Hospitality | 2024 |
| Devonshire Corporate Management Ltd | Real estate | 2010 |
| DH Executive Consultancy Limited | Professional & scientific | 2023 |
| Different Gravy (Sports) Limited | Wholesale & retail | 2019 |
| Digby Stamford PUB Group Limited | Hospitality | 2016 |
| Digital Beer Waste Management Limited | Administrative & support | 2026 |
| Digital Burrito Ltd | Professional & scientific | 2020 |
| Distinctive Developments Group Limited | Construction | 2015 |
| Diyyat Ltd | Professional & scientific | 2025 |
| Dizzy Dorris Limited | Wholesale & retail | 2015 |
| Djbrysonmedical Ltd | Health & social care | 2020 |
| DJS Engineering Limited | Professional & scientific | 2003 |
| Djssmith Ltd | Wholesale & retail | 2022 |
| DJW Management Services Ltd | Professional & scientific | 2015 |
| DMA Markets Limited | Financial services | 2008 |
| DME Slate Roofing Ltd | Construction | 2022 |
| DNA Creative Ltd | Arts & recreation | 2005 |
| DNM Logistics Ltd | Transport & logistics | 2021 |
| Docflow Solutions Limited | Other services | 2019 |
| Dolphin East Street Management Limited | Hospitality | 2015 |