The north–south Dublin Area Rapid Transit (DART) and Luas red line light rail services also pass through the station.

On 24 May 1844 the Dublin and Drogheda Railway (DDR) began public operations from an interim terminus at the Royal Canal, and on the same day the foundation stone for what is now Connolly station was laid by Earl de Grey, Lord Lieutenant of Ireland.

[citation needed] The terminus building, which was also to be the DDR's headquarters, designed by William Deane Butler, was constructed of Wicklow granite at a cost of £7,000 and opened in 1846.

[1] Originally the station served only a single mainline to Drogheda, and in 1853 through services to Belfast commenced,[citation needed] and an amalgamated company, the Great Northern Railway Ireland (GNRI) taking over operations.

Amiens Street Junction had through platforms, allowing passengers to travel over the Loopline Bridge to Westland Row on the city's Southside and onwards to Rosslare.

In 1937, the MGWR's Broadstone Station was closed, and the services to Sligo were transferred to Westland Row via Amiens Street Junction.

Connolly was selected as the eastern terminus after a part of the line through the Docklands was initially scrapped due to public opposition in 2000.

A heavy-rail link between the two stations has existed through the Phoenix Park Tunnel since 1877, which was historically only regularly used by freight trains and for the transfer of rolling stock and locomotives to the main service depot at Inchicore.

[12][13] An infrastructure project by Iarnród Éireann to improve signalling in Dublin city centre began in March 2015 and was placed in commission on 15 November 2020.

Built in an area in front of the main station entrance that was previously a bus terminus, the two Luas platforms are covered by a large, segmented canopy.

Less than half of all services on the Red Line serve Connolly, and signage at the platforms suggest that passengers make the short walk to Busáras Luas stop, where trams are more frequent.

[24][25] As the ferry terminal at the Port of Holyhead shares a building with Holyhead railway station, passengers can change by foot onto British trains along the North Wales Coast Line to Bangor, Llandudno Junction, Colwyn Bay, Rhyl, Prestatyn, Chester, Crewe and stations to London Euston.

A similar interchange exists at Fishguard Harbour station, which is served by trains to places including Carmarthen, Llanelli and Swansea.

The port in Cherbourg is near the town's railway station, which is served by TER Normandie regional trains to Gare Saint-Lazare in Paris.

These are: After years of delays,[citation needed] Irish Rail increased the DART frequency to every ten minutes in September 2018, which increased the number of trains per hour in Howth and Malahide to three, and those terminating at Bray Daly to four per hour—but kept Greystones at two per hour, with some peak services also terminating at Dún Laoghaire Mallin.

Peak time services also run to Longford, Hazelhatch, Newbridge, Dundalk Clarke, Balbriggan, Grand Canal Dock and Bray Daly.