The league said in a statement that the league has averaged 23,240 fans per game, breaking the 11 million-fan barrier for the first time in history.
MLS said the arrival of international stars such as Lionel Messi - whose presence in the league has often prompted teams to switch fixtures to bigger stadiums - had helped boost attendance.
"The arrival of international stars and the work from clubs to create more unique fan-friendly ticket packages and game day experiences are among the key drivers of the continued surge of record-breaking attendance across MLS," the league announced.
The record-breaking tally comes with the regular season still to be completed. Sixteen more matches are due to take place before the season wraps up on October 19th.
The attendance numbers mark the third consecutive year that MLS had drawn more than 10 million fans.