He guided the Senators to a 25-17-6 record this past season and was named the Jack Adams Award winner as the NHL's Coach of the Year.
"In two years, Paul has made a significant impact on the entire franchise, both on and off the ice," said Senators GM Bryan Murray. "We feel that under Paul's direction we have been able to develop into a team that is competitive each and every night and we are confident that he is the person we want behind the bench to lead us to our goal of being a championship level team."
In his first season with the club, MacLean led the Senators to a 41-31-10 record1.
In two years with the Senators, MacLean has compiled a record of 66-48-16 (.592 winning percentage) in 130 regular-season games.