In the WHL Playoffs, Zellweger scored 11-18=29 points with a +18 rating in 14 games. Despite being eliminated in the semifinals, he became one of two players to score 29 or more points in a WHL postseason since 1999 (also Derrick Pouliot in 2013-14). Zellweger ranked second among all WHL postseason leaders in points (11-18=29) and shots (92), third in goals, power-play assists (9) and plus/minus (+18), and tied for fourth in assists. He led all WHL defensemen in playoff points, goals, assists and shots. He was named WHL Player of the Week for the week ending April 23, recording 3-6=9 points in two playoff games, including a seven-point performance (3-4=7) April 20, 2023, tying the WHL playoff record for single-game points by a defenseman (also Darryl Sydor in 1991). He also scored 1-3=4 points in four Memorial Cup games this season.