1939–40 League of Ireland

The 1939–40 League of Ireland was the nineteenth season of the League of Ireland. Shamrock Rovers were the two-time defending champions.

St James's Gate won their second title.

Overview
No new teams were elected to the League.

Cork City withdrew on 13 February 1940. However, a new team, Cork United, were immediately elected in their place, being given special permission to complete Cork City's remaining fixtures.