It competed in the 2012 Hwarang Daegi National Youth Soccer Tournament and advanced into the finals; Baek received the GK (Goalkeeper) Award for his performance in the competition.

[3] The team also won all 16 of its matches at the 2015 National Secondary Soccer League Seoul Southern Region the following year; Baek was credited for its success, allowing only two goals to be scored against his club throughout the tournament.

[7] He, along with four others, signed a 5-year contract with FC Seoul, becoming the first of its players to have undergone the club's development system at both Osan Middle and High School.

[8] Baek made his debut professional appearance in the sixth round of the 2022 K League 1 season amid an outbreak of COVID-19 among his team's squad, which faced off against Jeju United FC on March 19.

[10] Midway through the year, he sustained an unspecified significant injury; FC Seoul recruited goalkeeper Seo Ju-hwan [ko] for the remainder of the season in Baek's absence.