Two new teams were elected to the League: Sligo Rovers returned after an eight-year absence, while Transport made their début.
This resulted in an expansion in size for the first time in six seasons, from eight to ten.
Cork United resigned from the League on 10 October 1948 and disbanded following their participation in the Dublin City Cup.
Cork Athletic were founded with a new board and elected in their place.
[1] Drumcondra successfully defended their title.