the most significant margin of victory in matches between the Chennai Super Kings (CSK) and the Mumbai Indians (MI) occurred on October 23, 2020, during the Indian Premier League (IPL) held in the United Arab Emirates. In this match, MI defeated CSK by 10 wickets with 46 balls to spare. This victory stands as MI's largest in terms of balls remaining against CSK. Sportzwiki
In terms of runs, CSK's most substantial win over MI was by 48 runs during the IPL 2013 season. NDTVSports.com
These matches highlight the intense and competitive nature of the CSK-MI rivalry in the IPL.