Businesses
- D and T Fitzgerald, solicitors
- D Devine and Sons
- D Harris and Son, billiard and bagatelle table manufacturers
- Daily Express
- Dairy Engineering Company of Ireland
- Dalby's Lodging House
- Daly and Elliott
- Daly and Ors
- Dame Street Picture House
- Daniel Murphy Limited, wholesale and retail provision merchant
- Dartry Dye Works, dyers and cleaners
- Davey and Company
- Davey's, public house
- David Allen and Sons
- David Drimmie and Sons
- David Towell Limited
- Davidson and Gaffyne, costume manufacturers
- Dawson and Company, librarians, stationers and fancy goods dealers
- Day and Martin Limited
- De Bear Schools
- De Selby Quarries Company Limited
- Department of Finance
- Dereenalomane Mines
- Disabled Crown Forces and Sailors Workrooms
- Distillers Company Limited
- Dobbyn and Company
- Dobson Molle and Company Limited
- Doherty's Hotel
- Dollard Printinghouse (Dublin) Limited
- Dollymount School of Musketry
- Dolphin Hotel
- Douglas Hotel and Restaurant
- Downes Brothers, carriage builders
- Dr Steeven's Hospital
- Drogheda Hospital
- DT Russell and Baird Company Limited
- Dublin and South Eastern Railway Company
- Dublin Asphalte and Flat Roofing Company
- Dublin Book Binding and Machine Ruling Company Limited
- Dublin Box Company Limited
- Dublin Bread Company Limited
- Dublin Brewery Company
- Dublin City Distillery
- Dublin Clothing Company
- Dublin Corporation
- Dublin Corporation Food Market
- Dublin Corporation Fruit Market
- Dublin Distillers Company Limited
- Dublin Distillers Grain Company
- Dublin Fire Brigade
- Dublin Granaries Company Limited
- Dublin Granary Stores
- Dublin Medical Mission
- Dublin Mercantile Association Limited
- Dublin Mercantile Permanent Building Society
- Dublin Metropolitan Police
- Dublin Motor Company
- Dublin Port and Docks Board
- Dublin Pure Ice and Cold Storage Company
- Dublin Salt Company Limited
- Dublin Savings Bank
- Dublin South City Market Company
- Dublin Steam Trawling Company Limited
- Dublin Swimming Club
- Dublin Towel Supply Company
- Dublin United Tramways Company Limited
- Dublin University Club
- Dublin Victuallers Association
- Dublin Wholesale Smallwares Company
- Dublin Working Boy's Home
- Duff Brothers
- Duke Shipping Company Limited
- Dundrum Castle
- Dunlop Laundry and Dye Works Limited
- Dunlop Rubber Company Limited
- Dunne's, pork butcher
- Dunshaughlin Rural District Council
- Dusmo Company Limited