| D.C.I. Holdings Limited | Professional & scientific | 2003 |
| D.E.M. Customs UK Limited | Wholesale & retail | 2018 |
| D.I.M Transport Ltd | Transport & logistics | 2018 |
| D.K.W. Engineering Limited | Manufacturing | 1969 |
| D.M Heating Ltd | Construction | 2013 |
| D.M.G. Motorcycles Limited | Wholesale & retail | 2018 |
| D.W.M Interiors Ltd | Construction | 2021 |
| D1 Mechanical Services Ltd | Energy | 2019 |
| D2I Developments Limited | Real estate | 2015 |
| D2I Property Maintenance Limited | Construction | 2009 |
| D3 Systems Fire and Security Limited | Administrative & support | 2024 |
| D4ST Ltd | Other services | 2023 |
| D84 Architects Ltd | Professional & scientific | 2010 |
| DA Bibby Properties Ltd | Real estate | 2023 |
| DA Construction Southern Limited | Construction | 2019 |
| DA Nonna Lucia Ltd | Manufacturing | 2025 |
| DAA Construction Ltd | Other services | 2011 |
| Dabouz Limited | Health & social care | 2021 |
| Dabras Homes Ltd. | Hospitality | 2023 |
| Dack Property Management Company Limited | Hospitality | 2004 |
| Dadandcloshow Ltd | Information & communication | 2025 |
| Dadzclub Limited | Information & communication | 2016 |
| Daedalus Drones Ltd | Professional & scientific | 2020 |
| Daily Food Line Ltd | Wholesale & retail | 2026 |
| DAIRY2DOOR Limited | Wholesale & retail | 2015 |
| Daisesexquisite Ltd | Administrative & support | 2025 |
| Daisy Capital Ltd | Construction | 2026 |
| Daisy Care Solutions Ltd | Administrative & support | 2022 |
| Daisy Cook Hair Limited | Other services | 2022 |
| Daisy Lettings and Property Management Limited | Real estate | 2021 |
| DAJ ARI Ltd | Real estate | 2024 |
| Dakota Business Park Management Company Limited | Real estate | 2007 |
| Dalara Ltd | Transport & logistics | 2026 |
| Dalav Ltd | Transport & logistics | 2016 |
| Daligar Limited | Construction | 2015 |
| Dallinson Ltd | Manufacturing | 2022 |
| Dalys Plumbing & Heating Ltd | Construction | 2018 |
| Dame Agnes Weston's Royal Charity for the Naval Service | Health & social care | 2017 |
| Damm Roofing Ltd | Construction | 2018 |
| Dan's Delights Ice Cream Van Ltd | Hospitality | 2020 |
| Dan's Houses Ltd | Real estate | 2024 |
| Dancepro Portsmouth Limited | Hospitality | 2024 |
| Dandelion Limited | Health & social care | 2010 |
| Dandy Tools Ltd | Wholesale & retail | 2016 |
| Dane Villas Developments Ltd | Construction | 2025 |
| Danecoat Properties Ltd | Real estate | 2013 |
| Daniamant Limited | Manufacturing | 2006 |
| Daniel Brown Properties Limited | Hospitality | 2026 |
| Danielle Jones Ltd | Professional & scientific | 2024 |
| Danilcom Construction Ltd | Construction | 2025 |
| Danny Homes Ltd | Real estate | 2018 |
| Danny Mart Ltd | Administrative & support | 2016 |
| Danny's Home Ltd | Real estate | 2023 |
| Danny's Hotel Ltd | Hospitality | 2019 |
| Danny'Trs Ltd | Administrative & support | 2018 |
| Dannys Store Ltd | Wholesale & retail | 2023 |
| Dansar Ltd | Manufacturing | 2026 |
| Danson Developments Ltd | Construction | 2016 |
| Daring Design UK Limited | Administrative & support | 2003 |
| Dariusz Makowski Ltd | Professional & scientific | 2017 |
| Dark Cosmos Creative Ltd | Manufacturing | 2015 |
| Dark Frame Ltd | Wholesale & retail | 2008 |
| Dark Lane Films Ltd | Administrative & support | 2014 |
| Darren Bendell Limited | Administrative & support | 2015 |
| Dartmouth Contractors Limited | Construction | 2019 |
| Dartmouth Group Ltd | Professional & scientific | 2020 |
| Darvill Ltd | Construction | 2024 |
| Dash Fluid Power (Consultants) Limited | Information & communication | 2002 |
| Dash-Dot Properties Limited | Real estate | 2018 |
| Data Decisioning Limited | Information & communication | 2014 |
| Data Dezign Ltd | Information & communication | 2013 |
| Data Mapping Ltd | Information & communication | 2025 |
| Data Point Ltd | Manufacturing | 2019 |
| Data Quest International Ltd | Information & communication | 1999 |
| Datara Management Solutions Limited | Administrative & support | 2004 |
| Dataroad Ltd | Information & communication | 2011 |
| Datum Woodwork Ltd | Construction | 2025 |
| Dave Binney Ltd | Construction | 2013 |
| Dave Treagust Photography Ltd | Professional & scientific | 2020 |
| Daves Diner Portsmouth Ltd | Hospitality | 2019 |
| David Irvin Amusements Limited | Arts & recreation | 2022 |
| David J Higgins Consulting Limited | Professional & scientific | 2016 |
| David Sanders Property Limited | Real estate | 2022 |
| David Turner Performance Labs Ltd | Wholesale & retail | 2024 |
| Davidia Developments Limited | Professional & scientific | 1973 |
| Davidlholmes Contracting Ltd | Manufacturing | 2014 |
| Davies Chemists (Havant) Limited | Wholesale & retail | 1938 |
| Davies Property Group Ltd | Real estate | 2023 |
| Davis Bellan Ltd | Wholesale & retail | 2021 |
| Davison & Fenwick Decorators Ltd | Construction | 2020 |
| Daward Associates Ltd | Professional & scientific | 2009 |
| Dawkins Aerospace Solutions Ltd | Manufacturing | 2016 |
| Dawn Homecare Solutions Limited | Health & social care | 2020 |
| Dawn Recruitment Limited | Administrative & support | 2017 |
| Dawnshore Limited | Real estate | 2000 |
| Day in Oriental Foods Store Ltd | Wholesale & retail | 2017 |
| Day's Estates (Southsea) Ltd | Construction | 2020 |
| Day's Lettings Ltd | Administrative & support | 2010 |
| Day's Properties IOW Limited | Financial services | 2023 |
| Daybreak Consulting Limited | Construction | 2018 |