John Shuster (Duluth, USA) qualified for the 2021 BKT Tires OK Tire World Men's Curling Championship playoffs, dropping their quarterfinals match 7-6 against Peter De Cruz (Geneva, SUI). of the 2021 BKT Tires OK Tire World Men's Curling Championship in Calgary, Alberta;
 
Shuster finished 10-3 in the 0 team BKT Tires OK Tire World Men's Curling Championship qualifying round, held April 2 - 11, 2021 in , . In their opening game, Shuster defeated Qiang Zou (Harbin, CHN) 5-4, then went on to lose 8-5 against Niklas Edin (Karlstad, SWE). Shuster responded with a 7-5 win over Sixten Totzek (Fuessen, GER). Shuster won 10-5 against Yuta Matsumura (Tokoro, JPN), then won 8-6 against De Cruz. Shuster went on to lose 10-1 against Brendan Bottcher (Edmonton, CAN). Shuster responded with a 8-2 win over Joel Retornaz (Pinerolo, ITA). Shuster went on to lose 11-8 against Sergei Glukhov (Moscow, RCF). Shuster responded with a 6-5 win over Steffen Walstad (Oppdal, NOR). Shuster won 10-9 against Bruce Mouat (Stirling, SCO), then won 8-3 against Mads Noergaard (Hvidovre, DEN) and 9-4 against Jaap van Dorp (Zoetermeer, NED). Shuster won 8-3 against Yeong Seok Jeong (Uijeongbu, KOR) in their final qualifying round match.
 
Shuster ranks 226th overall on the Year-to-Date rankings with 0.000 points earned so far this season.