The 2020–21 King Mindaugas Cup, also known as Citadele Karaliaus Mindaugo taurė for sponsorship purposes, was the sixth edition of the Lithuanian King Mindaugas Cup basketball competition.

Žalgiris successfully defended the title after defeating Lietkabelis in the final 76–69.

The top four placed teams from the LKL 2019–20 season, gained an automatic bye to the 2021 Karaliaus Mindaugo taurė quarterfinals.

Two highest ranked pair winners from 2019 to 2020 LKL season received bye's into Quarterfinals, while the remaining teams faced-off each other in a home-and-away format, with the overall cumulative score determining the winner of a match.

Top four teams from 2019–20 LKL season have received bye's to quarterfinals stage.