Businesses
- R and J Dick Limited
- R and J Wilson and Company, bakers and confectioners
- R and W Wilson and Sons Limited
- R Hornsby and Sons Limited
- R Hyde and Company Limited
- R Lehmann and Company Limited
- R Mitchell and Company Limited, manufacturer of upholsterers' trimmings
- R Scott, draper and milliner
- R Thorne and Sons Limited
- R White and Sons Limited
- Ragged Schools
- Railway Hotel
- Railway Refreshment Rooms
- Raimes and Company
- Raleigh
- Rambaut
- Rates Office
- Rathmines Amusements Company
- RE Turbett and Son
- Reckitt and Sons Limited
- Red Bank Restaurant Company Limited
- Red Cross
- Red Lion Hotel
- Redmond and Company, pawnbrokers
- Regimental Pay Office
- Reginald Dolman and Son
- Registrar of Marriages Office
- Reliance Advertising Limited
- Reliance Photo Engraving Company
- Representative Body of the Church of Ireland
- Resinol Chemical Company
- Reynolds, bicycle repairs
- Richard Allen, merchant tailor and clothier
- Richard Dickeson and Company Limited
- Richard F Barry and Son, solicitor
- Richard Pim and Son
- Richardson and Fletcher, chemical manure manufacturers and corn factors
- Richmond National Institute for the Blind
- Robert Buckham, gent's outfitters
- Robert Roberts and Company (Ireland) Limited
- Robert Smyth and Sons Limited, grocers and wine merchants
- Rockingham Arms Hotel
- Roger Greene and Sons
- Rooney and Company
- Rose Bower Dairy Company
- Rotunda Hospital
- Rotunda Theatre
- Rover Company Limited
- Rowe and Company
- Rowe Blue and Company
- Royal Army Medical Corps
- Royal Baking Powder Company of New York
- Royal Bank of Ireland Limited
- Royal College of Surgeons
- Royal Color Printing Works
- Royal Cooperative Collecting Society
- Royal Dublin Society
- Royal Engineers, 37th Divisional Signal Company
- Royal Exchange Hotel
- Royal Flying Corps
- Royal Hibernian Academy
- Royal Hospital
- Royal Hospital for Incurables
- Royal Hotel
- Royal Irish Constabulary
- Royal Irish Regiment
- Royal Irish Rifles
- Royal Mail Hotel
- Royal Marine Hotel
- Royal Navy
- Royal Nurseries
- Russell Hotel