The Scotland international joined the English Premier League outfit from Hibernian in 2018 and made a total of 299 appearances across all competitions.
In that time the midfielder has scored 33 goals and provided 41 assists.
Aston Villa manager Unai Emery said: "In the past three years, he has shown me how he is able to lead the team in all moments.
"He is a versatile player that can be used as a midfielder, winger and number 10. He is going to continue being an important player for us."
McGinn is the latest to sign a new contract with the club following defender Matty Cash last week.
Eleven people were arrested and hundreds of protesters gathered outside Villa Park on Thursday night as Aston Villa's Europa League match against Maccabi Tel Aviv unfolded under tight security.
Jadon Sancho's struggles deepened on Thursday night as the on-loan Manchester United winger failed to seize his opportunity in Aston Villa's 2-0 victory over Maccabi Tel Aviv.
Aston Villa marked Unai Emery's third anniversary in charge with another European win at Villa Park, while Nottingham Forest were left frustrated after being held to a goalless draw by Sturm Graz.
Manager Arne Slot said Liverpool finally earned the bit of good fortune they had been missing after ending their four-match Premier League losing run with a 2–0 victory over Aston Villa at Anfield on Saturday.
