Sheezel was already contracted until the end of 2030, but the 21-year-old is so convinced about North's direction he wanted to commit even longer.
North enter Sunday's match against Essendon boasting a 7-7 record, putting the club on track to make the wildcard finals round.
The last time North appeared in finals was in 2016, and there are big hopes they can finally break that 10-year drought.
Sheezel, the No.3 pick from the 2022 national draft, is already a two-time Syd Barker Medallist and also won the AFL's Rising Star award in 2023.
Against Richmond in round 23 last season, he equalled the all-time AFL/VFL record for most disposals in a single game, gathering 54 touches.
Sheezel is averaging a career-high 30.5 disposals and 4.9 clearances per game this season.
"Harry's quality as a player and person has been clear from the moment he walked through the door," North Melbourne head of football talent Brady Rawlings said.
"His leadership credentials were recognised early on by his teammates, who voted him into the leadership group in only his second season, and made him sole vice-captain this year."
Sheezel's contract extension follows on from George Wardlaw signing a two-year extension that runs until 2028, while forward Paul Curtis will remain a Kangaroo until at least the end of 2033.
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