The club went through the licensing procedures the following year however and on 20 February 2021 it was announced by the Football Association of Ireland that the club had been granted a licence and would take part in the 2021 League of Ireland First Division, taking the place of Shamrock Rovers II from the previous season.

The very presence of Treaty in the Markets Field is significant, as this is widely viewed as the historical, spiritual home of Limerick football.

[7] The club announced their 26-man first team squad and backroom staff for their first season in football under manager Tommy Barrett on 27 February 2021.

[8] They also announced that the number 4 shirt would be retired as a mark of respect to former Limerick United captain Joe O'Mahony.

The club exceeded expectations and finished in fourth place in their first season in the League of Ireland First Division, and were beaten 3-2 on aggregate v UCD in the playoffs.

Note: Flags indicate national team as defined under FIFA eligibility rules; some limited exceptions apply.