J.LEAGUE announced the competition format of the 2021 MEIJI YASUDA J3 LEAGUE. More details will be announced as soon as determined.
| Competition | Schedule and number of matches | Competition format |
| MEIJI YASUDA J3 LEAGUE (15 teams) | Saturday 13 March – Sunday 5 December, 30 rounds/210 matches | Home and Away round-robin competition |
* There is a possibility of that the schedule may change.
■Promotion and relegation rules between J2 LEAGUE and J3 LEAGUE
● The bottom four clubs of the J2 LEAGUE shall be relegated to J3 LEAGUE and the top two clubs of J3 LEAGUE shall be promoted to J2 LEAGUE
● J3 clubs that have not received a J.LEAGUE club license cannot be promoted and will not be replaced by third or lower place club
