Shamrock Rovers were the defending champions,[2] having won their sixth league title the previous season.
[3][4] Due to the impact of the COVID-19 pandemic on sports in the Republic of Ireland, the FAI met with the National League Executive Committee on 2 January 2021 and a decision was reached to move the start date for the Premier Division until at least 19 March 2021.
The promoted teams are Drogheda United and Longford Town, after respective top flight absences of four and five years.
[6][7] Note: Flags indicate national team as has been defined under FIFA eligibility rules.
*Note Sligo Rovers were awarded a 3–0 victory by the FAI after Waterford opted out of playing the game due to COVID-19 cases in their squad.