Businesses
- M Jordi and Company Limited
- M Kelly and Son
- M Kosmack and Company
- M Rowe and Company
- MacGregor and Selly
- MacInerney and Company, general drapers
- MacSymon's Stores
- Madame A Drago, Parisian hairdresser and wigmaker
- Maguire and Gatchell Limited
- Maison Phillippe
- Maison Prost Limited
- Manfield and Sons, boot and shoe warehouse
- Marconi's Wireless Telegraph Company Limited
- Margaret J Lowry, pawnbroker
- Marie Freeman, bacon merchants
- Mark Carolan, clerical and merchant tailor
- Market and Company (London) Limited
- Marks and Company
- Markt and Company Limited
- Marlborough Hotel
- Marr Downie and Company Limited
- Marsh and Company Limited
- Martin Fitzgerald and Company
- Martin Pulverman and Company
- Mary Bolger, publican
- Masonic Female Orphan School
- Masterpiece Picture Palace
- Masters and Andren Limited
- Matheson and Prentice, solicitors
- Maunsel and Company Limited, publishers
- Maxwell Weldon and Company
- May and Sons, professors of music, pianoforte and music sellers
- Maypole Dairy Company Limited
- Mazawattee Tea Company Limited
- McBirney and Company Limited, wholesale and retail linen drapers
- McCann's stores
- McCarthy and Company, costume and mantle warehouse
- McCaughey Hotels and Restaurants Limited
- McDonald Brothers
- McDowell Brothers, watchmakers and jewellers
- McGivney, cutler
- McGrath Brothers
- McLoughlin Brothers
- McMaster Hodgson and Company Limited, wholesale druggists and oil merchants
- McNally's, pawnbrokers
- Meagher's public house
- Meath Hotel
- Mecredy Percy and Company Limited, publishers
- Meldon and Company, solicitors
- Mendicity Institute
- Menzies and Company, millinery and ladies' underclothing
- Messrs Townshend, land agents
- Methodist Church
- Methodist Windows Alms House
- Metropole Hotel
- Metropolitan Hall
- MH Gill and Son Limited
- Michael McInerney, grocer
- Middlesex Regiment
- Midland Great Western Railway
- Midland Railway of England
- Mill Park Brewery
- Mill's Bakery
- Milward Jones and Cameron, solicitors
- Mirror Laundry Dublin Limited
- Miss Connolly, dress warerooms
- Miss Fitzpatrick, dressmaker
- Misses Gannon, costumiers and ladies' tailor
- Missions to Seamen Institute and Sailor's Reading Room
- Mitchell and Company
- MJ Cahill, tailor, clothier and outfitter,
- Model School
- Molassine Company Limited
- Montgomery and Chaytor, solicitors
- Mooney and Company
- Moore Brothers
- Moore Street Market
- Moore's public house
- Moran and Company
- Moran's Hotel
- Morgan Crucible Company Limited
- Morgan Fottrell, solicitor
- Morris and Company, tailors and outfitters
- Morris and Jones Limited
- Moss and Gray, wholesale coffee and cocoa merchants
- Mountjoy Brewery Limited
- Munster and Leinster Bank
- Munster Hotel
- Murphy Brothers
- Murphy, Byrne and Walcott