ADELAIDE young gun Tom Doedee has signed a two-year contract extension with the Crows until the end of 2021.

The 21-year-old had another 12 months to run on his previous deal, but the Crows have been quick to lock in the intercept-marking defender's signature after an outstanding breakout season.

After not playing a senior game in his first two years on the list, Doedee played 20 out of a possible 22 games in 2018, averaging 18 disposals and 2.2 intercept marks per game, finishing second in the NAB AFL Rising Star award and seamlessly replacing Jake Lever, who moved to Melbourne at the end of last season.

The only two games Doedee missed this year were due to concussion and a broken collarbone, suffered in round 22.

"I'm absolutely rapt to sign on for another two years," Doedee said.

"I love this club, and everyone – my teammates, coaches and staff – have really made me and my family feel a part of the footy club since day one.

"It was a dream come true to play senior footy this year, and while I'm pretty happy with my own season, I'd much rather be playing in finals right now.

"I am confident we have the right people in place to bounce back and enjoy team success in 2019."

Crows general manager of list management and strategy Justin Reid said Doedee was a valuable part of the playing group.

"Tom has had a fantastic year, which is a credit to his selfless attitude and work ethic," Reid said.

"He has worked extremely hard to get to this point and showed this season he has a very bright future at AFL level."

Doedee was selected with the 17th overall pick in the 2015 National Draft.