Harley's new deal will go into effect starting next season and will carry an average annual value of $10.587 million through the 2033-2034 season.
The former 18th overall pick in the 2019 NHL Draft is coming off back-to-back seasons with at least 15 goals and 30 assists.
He made his debut with the Stars during the 2021-2022 season, playing in 34 games. But after a lackluster rookie season, posting just one goal and three assists, he spent the majority of the following season in the AHL before blossoming during the 2023-2024 year when he put up 15 goals and 32 assists through 79 games.
Harley currently has one goal through the Stars' first 10 games, but his seven assists are tied with teammate Roope Hintz - a center - for second-most on the team and the most among all Dallas defencemen, with Esa Lindell behind him with three.
The Stars are currently 6-3-1 and are riding a three-game win streak as they prep for their next game against the Tampa Bay Lightning on Thursday, October 30th.