| Dale Minerals Limited | London | 2019 |
| Dalgarno General Services (DGS) Ltd | Keith | 2019 |
| Dalmahoy Engineering Services Limited | Kirkcaldy | 2013 |
| Dalradian Gold Limited | Omagh | 1971 |
| Damien Hardy Ltd | Alton | 2026 |
| Damotec Ltd | Lowestoft | 2003 |
| Dana Offshore Consultancy Ltd | Burnham-On-Sea | 2024 |
| Dana Petroleum (Bvuk) Limited | London | 1997 |
| Dana Petroleum (E&P) Limited | London | 1988 |
| Dana Petroleum (East MED) Limited | London | 2022 |
| Dana Petroleum (North Sea) Limited | London | 1989 |
| Danaig Services Ltd | Insch | 2018 |
| Danbury Aggregates Limited | Danbury | 2011 |
| Danbury Haulage (Landfill) Limited | Danbury | 2002 |
| Danbury Haulage (Oak Landfill) Limited | Danbury | 2011 |
| Danbury Haulage (Oak Quarry) Limited | Danbury | 2010 |
| Danbury Haulage (ST. Cleres) Ltd | Danbury | 2008 |
| Danby Associates Limited | Teddington | 2008 |
| Daned Consultancy Services Limited | Hailsham | 2012 |
| Dani & Denisa Transport Limited | Coventry | 2017 |
| Daniel Benn Services Limited | Maidstone | 2025 |
| Daniel Cameron Ltd | Fochabers | 2023 |
| Daniel Scrimshaw Professional Bolting Services Limited | Morpeth | 2015 |
| Danny Offshore Ltd | Plymouth | 2019 |
| Dantech Energy Limited | Lowestoft | 2013 |
| Danube Petroleum Limited | Dudley | 2017 |
| Danum Well Services Limited | Doncaster | 1999 |
| DAR DAR Enterprises Ltd | Sheffield | 2023 |
| DAR Oilfield Logistics Ltd | Forres | 2015 |
| DAR Rope Access Limited | Edinburgh | 2014 |
| Daraa Ltd | Preston | 2026 |
| Darby Industrial Ltd | London | 2021 |
| Darby Services Ltd | Great Yarmouth | 2026 |
| Dargaval Investments Ltd | Newcastle Upon Tyne | 2025 |
| Dargavel Contracts Ltd | Bishopton | 2019 |
| Dark Star Petroleum Limited | Watford | 2011 |
| Darkside Drilling Limited | Peterhead | 1999 |
| Darkwater Construction Ltd | Perth | 2011 |
| Darren Rudd Services Ltd | Norwich | 2013 |
| Darren Steven NDT Ltd | Dundee | 2020 |
| Darren’S Rigging Ltd | Stockton On Tees | 2023 |
| Darron Tool and Engineering (Sheffield) Limited | Chesterfield | 1969 |
| Darrus Drilling Consultants Limited | Macduff | 2019 |
| Dart Energy (East England) Limited | Lincoln | 2008 |
| Dart Energy (Europe) Limited | Edinburgh | 2003 |
| Dart Energy (West England) Limited | Lincoln | 2008 |
| Datamine Corporate Limited | Bristol | 1982 |
| Dataqual Ltd | Norwich | 2013 |
| Datta Engineering Consultancy Limited | Harrow | 2007 |
| Dave.T Services Ltd | Arbroath | 2026 |
| Davenhill Quarries Holdings Limited | Brierley Hill | 2019 |
| Davenhill Quarries Land Ltd | Brierley Hill | 2024 |
| Davenport Minerals Ltd | St. Neots | 2026 |
| David Baker Offshore Ltd | Houghton Le Spring | 2026 |
| David Bernard Ltd | Wellington | 2007 |
| David Brown Inspection Services Ltd | Banbridge | 2013 |
| David Fielding Services Limited | Worcester | 2005 |
| David Leitch Inspection Services Ltd | Glasgow | 2012 |
| David Meredith & Sons Limited | Gwynedd | 2003 |
| David O'Farrell Electrical Limited | Blackpool | 2012 |
| David R Hunter Limited | Prestonpans | 2017 |
| David Ritchie & Sons Limited | Carrbridge | 2002 |
| David Wright Limited | Exeter | 2024 |
| Davids Energy Limited | London | 2023 |
| Davidson Project Management Solutions Ltd | Aberdeen | 2026 |
| Davlor Limited | Craigavon | 2015 |
| Davy Access Limited | Bedlington | 2008 |
| Dawson Offshore Limited | Great Yarmouth | 2011 |
| Dayal Control Systems Limited | Greenford | 2013 |
| DB GAS & OIL Ltd | Prescot | 2019 |
| DBG Offshore Services Limited | Crook | 2025 |
| DBI Holdings Ltd | Crewe | 2010 |
| DBT Ropes and Rigs Ltd | Billericay | 2022 |
| DC ROV Services Limited | Elgin | 2026 |
| DC SUB Sea Ltd | Macclesfield | 2012 |
| DCB Drilling Consultant Ltd | Inverurie | 2022 |
| DCI Global Solutions Ltd | Southampton | 2021 |
| DCN Diving UK Limited | Dyce | 2013 |
| Dcoute & Investments Ltd | Beckton | 2018 |
| DCT Mechanical Ltd | Blyth | 2025 |
| DD Inspection Maintenance Ltd | Swansea | 2023 |
| DDE Peterhead Ltd | Peterhead | 2017 |
| Dders Global Mining Ltd | Pimlico | 2012 |
| DDG OIL & GAS Ltd | Dundee | 2025 |
| DDL Rigging Ltd | Peterhead | 2019 |
| DDM OIL Services Ltd | Elgin | 2022 |
| Ddraig R & L Ltd | Falmouth | 2026 |
| DE Offshore Electrical Limited | Huddersfield | 2013 |
| Dean Hall Minerals Ltd | Whitby | 2012 |
| Dean Quarry Mineral Rights Limited | Gloucester | 2014 |
| Deane Southwest Ltd | Swaffham | 2015 |
| Decaulin (UK) Limited | London | 2023 |
| DECIMAL99 Ltd | London | 2024 |
| Decom Energy (NO.1) Limited | London | 2019 |
| Decom Energy Limited | London | 2015 |
| Deep Casing Tools Limited | Westhill | 1999 |
| Deep Sea Atlantic (UK) Ltd | Eastleigh | 2017 |
| Deep Sea RIG (UK) Ltd | Eastleigh | 2024 |
| Deep Sea Stavanger (UK) Ltd | Eastleigh | 2017 |
| Deep SIX Engineering Ltd | Epsom | 2025 |