Walsh, the No.1 draft pick last year, has made an instant impact in four AFL games in his debut season.

His fresh deal ties him to Carlton until the end of the 2022 season.

"The club has welcomed me with open arms from the moment I got drafted," the 18-year-old told Carlton's website on Wednesday.

"What struck me straight away was the elite standards our club has in place ... that has us focused as a young group to fast-track our development and achieve success."

The latest Rising Star nominee has averaged 26.3 disposals a game, prompting praise from Carlton's list manager Stephen Silvagni.

"We could not have asked much more of Sam with the way he has approached his football from the moment he walked through the door," Silvagni told the club's website.

"From that day on, his sole focus has been to make himself the best player he can possibly be.

"He is an impressive young player and a really quality person."

Walsh joins co-captain Patrick Cripps (contracted until the end of 2021), Zac Fisher (2021), Sam Petrevski-Seton (2021) and Paddy Dow (2022) in signing long-term deals with Carlton.

Australian Associated Press