The 2018 number one draft pick and 2019 AFL Rising Star had a four-year contract that was due to expire at the end of 2026, placing him in free agency territory with some other big names such as Zak Butters and Zac Bailey.
Walsh and the Blues have ended weeks if not months of distracting speculation by securing his future two weeks out from the beginning of the season.
His long-term commitment to the club makes him a leading candidate to be a future captain, having been described by list manager Nick Austin as "an exceptional leader (and) someone who sets the tone both on and off the field".
The deal is reportedly worth at least $10 million, which would make it the most expensive in club history.
Walsh spoke on Tuesday morning of his delight to potentially be at Ikon Park for 15 or more years.
“I love this Club. I am a Carlton person and I couldn’t be happier to continue my career here,” Walsh wrote in a Carlton statement.
“This was obviously a big decision for me, but it was made so much easier because I know we are heading in the right direction. I make no secret of the fact that I want to win, and I want to win with the Carlton monogram on my chest.
“I truly believe that the key people we have here, and where our group is at right now, we are seeing a significant shift as we head into this next period of our football club, one that I know is going to be really exciting to be part of.
“When I arrived, our Club was last on the ladder. Footy isn’t a linear experience, everyone knows that, but I am all in on the next eight years and doing everything I can to help us reach the top and stay there - the day we do will mean everything to me.
“The Carlton family is like no other: the roar, the passion is unbelievable. To continue to share that with you all, I can’t wait - it is going to be special to do that together.”