Businesses
- H and G Simonds Limited
- H and J Martin Limited
- H Whitaker and Company Limited
- H Williams and Company Limited
- Hall and Hall
- Hamilton and Company
- Hamilton Long and Company Limited
- Hammond Lane Foundry
- Hampton Leedom and Company Limited, hardware merchants
- Harmens Motor Agencies Limited
- Harris and Greene, solicitors
- Harrison and Company, cooks and confectioners
- Harrod's Limited
- Hayes and Sons, solicitors
- Hayes, Conyngham and Robinson Limited
- HB Cunningham, pawnbroker
- HD Vaughan, solicitor
- HE Hunt Limited
- HE Randall Limited, boot and shoe manufacturers
- Hearne and Cahill
- Heavey Brothers
- Hely's Limited
- Henry and James
- Henry and Son, solicitors
- Henry Fletcher and Company Limited
- Henry Grandy, art tailor and outfitter
- Henry Pattison and Company Limited
- Henry Smith Limited
- Henry Street Warehouse Company Limited
- Henry Tate and Sons Limited
- Heydon and Company
- Hibernian Bank Limited
- Hibernian Bible Society
- Hibernian Fire and General Insurance Company
- Hibernian Hotel
- Hibernian Lace Company
- Hibernian United Service Club
- Hickey and Company
- Hilton Parsley and Company Limited
- Hipps Limited
- Hodges and Sons Limited, house furnishing and ironmongers
- Hodges Figgis and Company Limited, publishers and booksellers
- Hogg and Company Limited
- Hogg and Robertson Limited
- Holyhead Hotel
- Home and Colonial Stores Limited
- Home Pride flour mills
- Honourable Society of King's Inns
- Hopkins and Hopkins, jewellers
- Horan and Son
- Horticultural Seed Warehouse
- Hoseas Weiner and Company, furniture dealer
- Hospice for the Dying
- Hotel Allen
- Hotel and Tourist Association of Ireland
- Hotel Europa
- Hoynes Hotel
- Hoyte and Son, druggist
- HT Dix and Sons
- Huet Brothers, cycle and motor accessories factors
- Hugh Brady, tea and wine merchants
- Hugh Moore and Alexanders Limited, wholesale druggists
- Humber Limited, motor and cycle manufacturers
- Humphreys and Company
- HVV Thompson, solicitor