Each MEX1 team plays Home-Away matches with the other 17 MEX1 teams once in the 2020-2021 Torneo Guard1anes (17 matches) and once in the 2021-2022 Torneo Clausura (17 matches) for a total of 34 league matches per team. Table ranking ties are broken by (1) goal difference, (2) goals scored, (3) head-to-head results between tied teams, (4) away goals scored, (5) highest relegation coefficient, then (6) Fairplay points.

At the end of each torneo, the top four teams advance to the La Liguilla (the playoffs) Quarterfinals, and the 5th through 12th place teams advance to the Reclasificación. In the Reclasificación, 5th place plays 12th place, 6th place plays 11th place, 7th place plays 10th place, and 8th place plays 9th place in a single match playoff at the higher seed's home venue. If a match is tied after regulation time, the teams advance to a best of 5 penalty shoot-out. The winners play in Home-Away highest aggregate score advances Quarterfinals. The four advancing teams play in a Home-Away highest aggregate score advances Semifinals. The two Semifinal winners advance to the Finals with the winner becoming the torneo champion. All Torneo Finalists advance to the 2021-2022 CNCFCL.

At the end of the 2020-2021 Torneo Clausura, the results from the 2020-2021 Toreno Apertura, the 2020-2021 Torneo Clausura and the two previous seasons are used to build the 2020-2021 MEX1 Relegation Table. The MEX1 team with the lowest "points per match" ratio is relegated to the MEX2. The MEX2 champion is promoted to the 2021-2022 MEX1 Torneo Apertura.