| DI LA Varton Limited | Real estate | 2015 |
| DI Property Limited | Real estate | 2025 |
| DI Santi Limited | Wholesale & retail | 2018 |
| Di-Log Limited | Wholesale & retail | 1998 |
| Di-Tec Power Limited | Wholesale & retail | 1994 |
| Diaa Property Management Ltd | Real estate | 2025 |
| Diablo Events Limited | Hospitality | 2025 |
| Diablo Group Limited | Wholesale & retail | 2024 |
| Diablo Initiative Limited | Construction | 2024 |
| Diabro Estates Ltd | Real estate | 2022 |
| Diacons Ltd | Health & social care | 2020 |
| Diadem Courier & Logistics Services Ltd | Transport & logistics | 2025 |
| Diag Trade Ltd | Wholesale & retail | 2024 |
| Diaga Catering Limited | Hospitality | 2024 |
| Diagnostic Healthcare Limited | Health & social care | 2004 |
| Diagonal Property Holdings Ltd | Real estate | 2024 |
| Diagonal Thinking Ltd | Professional & scientific | 2021 |
| Diah Pharm Ltd | Professional & scientific | 2018 |
| Dial Concepts Ventures International Limited | Administrative & support | 2024 |
| Dial Consult Limited | Real estate | 2019 |
| Dial Direct Limited | Professional & scientific | 1990 |
| Dial Health Care Ltd | Health & social care | 2016 |
| Dial Tameside | Health & social care | 1989 |
| Dial Telecom Ltd | Education | 2014 |
| Dial Ventures Limited | Administrative & support | 2017 |
| Dialed. Ltd | Manufacturing | 2024 |
| Dialerus Ltd | Transport & logistics | 2019 |
| Dialfix Ltd | Wholesale & retail | 2024 |
| Dialforflight Ltd | Administrative & support | 2026 |
| Diallo Trading Ltd | Extraterritorial | 2015 |
| Diallouk Ltd | Transport & logistics | 2025 |
| Dialmode (328) Limited | Financial services | 2006 |
| Diamas Consulting Ltd | Professional & scientific | 2023 |
| Diamene Resilience Limited | Administrative & support | 2020 |
| Diamology Limited | | 1980 |
| Diamond Aerials & Satellites Limited | Construction | 2011 |
| Diamond Beam Ltd | Wholesale & retail | 2013 |
| Diamond Blue Holdings Ltd | Financial services | 2024 |
| Diamond Blue Limited | Wholesale & retail | 2010 |
| Diamond BOI Ltd | Information & communication | 2020 |
| Diamond Business Development & Management UK Limited | Information & communication | 2022 |
| Diamond Cabby (UK) Limited | Transport & logistics | 2025 |
| Diamond Car Parks Limited | Other services | 2016 |
| Diamond Car Wash Manchester Ltd | Administrative & support | 2021 |
| Diamond Care International Group Ltd | Wholesale & retail | 2025 |
| Diamond City Property Limited | Real estate | 2015 |
| Diamond Class Ltd | Information & communication | 2025 |
| Diamond Coatings Northwest Limited | Construction | 2025 |
| Diamond Construction Manchester Ltd | Construction | 2021 |
| Diamond Cutz MCR Ltd | Wholesale & retail | 2025 |
| Diamond Design Alloys Limited | Wholesale & retail | 2015 |
| Diamond Development Limited | Real estate | 2024 |
| Diamond Development Services Ltd | Construction | 2021 |
| Diamond Disposal Co Limited | Wholesale & retail | 2014 |
| Diamond Dream Jewels Ltd | Wholesale & retail | 2024 |
| Diamond Edge Business Advisors Ltd | Extraterritorial | 2026 |
| Diamond Empire Cleaning Services Ltd | Administrative & support | 2024 |
| Diamond Estate Group Ltd | Real estate | 2025 |
| Diamond Estate Ventures Ltd | Real estate | 2024 |
| Diamond Estates Ltd | Real estate | 2019 |
| Diamond Estates North West Limited | Real estate | 2024 |
| Diamond Frame Snooker Limited | Arts & recreation | 2025 |
| Diamond Freight & Warehousing Ltd | Transport & logistics | 2025 |
| Diamond Global Ltd | Wholesale & retail | 2025 |
| Diamond H TRAC360 Ltd | Transport & logistics | 2013 |
| Diamond Hand Car Wash M/C Ltd | Other services | 2015 |
| Diamond Health & Safety Limited | Professional & scientific | 2003 |
| Diamond Heart Health Care Ltd | Health & social care | 2020 |
| Diamond Icon Ltd | Administrative & support | 2012 |
| Diamond Industries Limited | Mining & quarrying | 2020 |
| Diamond IT Consultant Ltd | Information & communication | 2012 |
| Diamond Laundry MAN Ltd | Other services | 2025 |
| Diamond Laundry NW Services Limited | Other services | 2025 |
| Diamond Logistics ( NW ) Limited | Transport & logistics | 2025 |
| Diamond Melee Ltd | Wholesale & retail | 2023 |
| Diamond Network for Commercial Supplies Ltd | Wholesale & retail | 2025 |
| Diamond Point Limited | Construction | 1992 |
| Diamond Property Solutions Manchester Limited | Real estate | 2021 |
| Diamond Protocol Limited | Information & communication | 2025 |
| Diamond Quality Construction Ltd | Construction | 2026 |
| Diamond Quality Construction Private Ltd | Construction | 2019 |
| Diamond Recovery and Storage Ltd | Wholesale & retail | 2025 |
| Diamond Removal Ltd | Transport & logistics | 2019 |
| Diamond Sparkle Car Wash Ltd | Wholesale & retail | 2025 |
| Diamond Special Kebab Ltd | Hospitality | 2026 |
| Diamond Transmission Corporation Limited | Energy | 2013 |
| Diamond Travel (N/W) Ltd | Transport & logistics | 2026 |
| Diamond Tyre Service Ltd | Wholesale & retail | 2020 |
| Diamond Tyres 1 Ltd | Other services | 2025 |
| Diamond Upholstery Ltd | Other services | 2019 |
| Diamond V Ltd | Administrative & support | 2020 |
| Diamond Valeting Limited | Other services | 2025 |
| Diamond White DRY Cleaners Ltd | Other services | 2020 |
| Diamond World Limited | Construction | 2023 |
| Diamond World Trading Limited | Wholesale & retail | 2023 |
| DIAMOND2K Limited | Manufacturing | 2014 |
| Diamonddesires Concierge Ltd | Wholesale & retail | 2025 |
| Diamondplus Cleaning Ltd | Administrative & support | 2026 |
| Diamondplus Healthcare Ltd | Hospitality | 2024 |
| Diamonds ARE Forever Limited | Wholesale & retail | 2011 |