The Midland Great Western Railway's line from Mullingar to Longford was opened in 1855, with the final section to the large county town of Sligo opening in December 1862. Sligo Station, which originally consisted of an arrival and departure platform flanked by carriage sidings, had an overall roof but this was destroyed in 1922 during the civil war. the roof been replaced by basic canopies hung from the tall stone built retaining walls. At the south end of the station is the now redundant MGWR style signal cabin, though with a re-bricked base.
As part of the upgrading of the Sligo line, the station now only has one operational platform, with a siding serving the former arrival platform. At the south end of the station is the former water tower, turntable, and one time engine shed which demolished in the 1980s. The now disused branch line from Sligo Quay freight yard also converges at the south end of the station, where a run around loops is provided for locomotive hauled trains.