[9] His last year at Yonsei ended on a sour note when Yonsei lost to rival Korea University in the annual "friendship games" as well as all three major collegiate titles: being knocked out by Korea University in the MBC Cup quarter-finals, finishing runner-up to them in the U-League regular season standings and losing to them in the championship finals.

However, he impressed in the MBC Cup quarter-final loss to Korea University by scoring 27 points, including eight 3-pointers, and caught the attention of KBL scouts.

[9] Heo declared for the 2014 KBL rookie draft and it was widely predicted that he would be picked by Jeonju KCC Egis, which was then coached by his father Hur Jae.

Jeonju KCC Egis had been assigned the fourth pick but Hur Jae chose Kim Ji-hoo from Korea University instead to prevent his son's career from being overshadowed.

[13] By the end of the season, he had established himself in the team and won the Most Improved Player Award, having averaged 12.03 points and playing in all 54 league games.

[14][15] In May 2017, Heo enlisted for mandatory military service and was assigned to the Sangmu team [ko] after completing basic training.

[18] Heo was plagued by persistent back and ankle problems during the 2019–20 season but averaged a career-high of 13.7 points in 14 games and ranked second for 3-point shots among domestic-born players.

Due to injury problems ravaging the team throughout the season, the players had little time to gel and Heo occasionally had to play despite not being in peak physical condition.

[35][36] Early on, during his father's tenure as the national team coach, Heo's selection was constantly a source of criticism and accusations of favouritism, which came to a head after South Korea failed to defend their gold medal at the Asian Games.

Following his good form during the 2021–22 season, he was named in the squad to face the Philippines for a series of pre-2022 FIBA Asia Cup friendly games and was the first-option shooting guard.

[42][43][44] Heo is the older son of retired South Korean basketball player and former national team coach Hur Jae.