| Cyrus Pharma Ltd | Health & social care | 2023 |
| D & K Oral Care Ltd | Households | 2018 |
| D J Granger Grounds Maintenance Limited | Administrative & support | 2003 |
| D M Financial Advice Limited | Financial services | 2017 |
| D&E Pharma Trading Ltd | Wholesale & retail | 2026 |
| D&S Decorating Limited | Construction | 2023 |
| D&S Decorating Services Limited | Construction | 2019 |
| D-Logic Ltd | Financial services | 2025 |
| D.& B.Developments Limited | Information & communication | 1964 |
| D.G. Owens Limited | Professional & scientific | 1988 |
| D.P. International Limited | Wholesale & retail | 1999 |
| D3MOO Limited | Wholesale & retail | 2011 |
| DA Costa Creations Ltd | Manufacturing | 2022 |
| DAA Limited | Wholesale & retail | 2009 |
| DAA Restaurant Ltd | Extraterritorial | 2014 |
| Daaz Nordic Limited | Wholesale & retail | 2022 |
| Dach Real Estate Limited | Real estate | 2025 |
| Dacs Holdings Limited | Financial services | 2025 |
| DAI UK | Education | 2006 |
| Daktari Ltd | Information & communication | 2024 |
| Daniel Nash Accounting Services Limited | Professional & scientific | 2012 |
| Daniel Webb Property Ltd | Real estate | 2022 |
| Danks Badnell Architects Limited | Professional & scientific | 2013 |
| Danks Badnell Holdings Ltd | Financial services | 2020 |
| Darling Buds Hire & Events Ltd | Hospitality | 2025 |
| Darling Buds of Wiindsor Ltd | Wholesale & retail | 2026 |
| Darq Studios Limited | Arts & recreation | 2015 |
| Darq Technologies Limited | Information & communication | 2019 |
| Dasa Commercial Investments Limited | Real estate | 2023 |
| Dasa Investment Holdings Limited | Financial services | 2021 |
| Dasa Investments Ltd | Hospitality | 2011 |
| Dasa Property Investments Limited | Real estate | 2021 |
| Dashwarninglights Limited | Wholesale & retail | 2017 |
| Dastur Limited | Transport & logistics | 2015 |
| Data Safe Networks Limited | Information & communication | 2024 |
| Data Tech City Ltd | Extraterritorial | 2019 |
| Datafonica (UK) Limited | Information & communication | 2006 |
| Datalnk Solutions Limited | Information & communication | 2015 |
| Datamax Corporation | | 1992 |
| Datchet Lodge Residents Company Limited | Households | 1994 |
| Dating Agency Association | Other services | 2013 |
| Davandri Ltd | Professional & scientific | 2020 |
| Dave a Metal Limited | Manufacturing | 2010 |
| David Crofts Limited | Arts & recreation | 2008 |
| David Epstein Consulting Ltd | Professional & scientific | 2020 |
| David Walters Life Sciences Consultancy Ltd | Professional & scientific | 2023 |
| Davies Mobile Maintinance Limited | Wholesale & retail | 2026 |
| Davin & Danya Property Ltd | Real estate | 2025 |
| Davis Supply Chain Management Limited | Professional & scientific | 2018 |
| Davisan Properties Limited | Real estate | 2024 |
| Dawhra Research Limited | Information & communication | 2015 |
| Dawn Consultants M&E Ltd | Professional & scientific | 2026 |
| Dawn Newton Ltd | Professional & scientific | 2014 |
| Dawnverge Residents Association Limited | Households | 1983 |
| Daytimelive Ltd | Health & social care | 2019 |
| Daywin Group Ltd | Wholesale & retail | 2025 |
| DC Insights Ltd | Professional & scientific | 2026 |
| DC Tech Ltd | Wholesale & retail | 2025 |
| DE LE Cuona Designs Limited | Wholesale & retail | 1996 |
| DE LE Cuona UK Holdings Limited | Financial services | 2022 |
| DE Minds Ltd | Health & social care | 2025 |
| DE VIL Properties Ltd | Real estate | 2023 |
| Deacon Court Management Company (Windsor) Limited | Households | 1977 |
| Dean Wright UK Limited | Construction | 2018 |
| Deanfield (Bledlow) Management Company Limited | Households | 2022 |
| Deanfield (Cholsey) Management Company Limited | Households | 2020 |
| Deanfield (Dinton) Management Company Ltd | Households | 2024 |
| Deanfield (East Hagbourne) Management Company Limited | Households | 2022 |
| Deanfield (Ickford) Management Company Limited | Households | 2021 |
| Deanfield (Marsh Gibbon) Management Company Limited | Households | 2021 |
| Deanfield (Sibford Ferris) Management Company Ltd | Households | 2023 |
| Deanfield (Stanton Harcourt) Management Company Limited | Households | 2021 |
| Decent Shop Front Shutters Limited | Construction | 2017 |
| Dede Tailoring Ltd | Manufacturing | 2018 |
| Dedworth Manor RTM Company Limited | Households | 2006 |
| Dedworth Road Management Company Limited | Households | 1975 |
| Deep Forest Carpentry Limited | Manufacturing | 2000 |
| Deeva MPS Ltd | Professional & scientific | 2024 |
| Degree Limited | Construction | 2007 |
| Delamack Ltd | Professional & scientific | 2020 |
| Delaney Pharmaceutical Consulting (DPC) Ltd | Professional & scientific | 2025 |
| Delight Mart Ltd | Wholesale & retail | 2025 |
| Delivet Consulting Ltd | Professional & scientific | 2014 |
| Delorange Ltd | Construction | 2007 |
| Delyvan Limited | Transport & logistics | 2024 |
| Deneb Marine Services Ltd | Other services | 2022 |
| Denham Hand Car Wash Ltd | Administrative & support | 2025 |
| Denham Valeting and Detailing Ltd | Wholesale & retail | 2026 |
| Denny Armatrading Media Limited | Information & communication | 2012 |
| Denove Services Ltd | Professional & scientific | 2011 |
| Design Rows Limited | Information & communication | 2023 |
| Design Soloutions Limited | Construction | 2018 |
| Designed in Wimbledon Ltd | Construction | 2023 |
| Designworks 2 Limited | Administrative & support | 2021 |
| Designworks Windsor Limited | Administrative & support | 2002 |
| Devinchi Cohan Ltd | Construction | 2021 |
| DGK Financial Limited | Professional & scientific | 2023 |
| DH Bikes and Cars Limited | Wholesale & retail | 2024 |
| Dhruva Limited | Information & communication | 2012 |
| Diagnostic Health Limited | Manufacturing | 2019 |