Ju made his league debut for Busan IPark as a substitute in 6–0 defeat away to FC Seoul on 21 July 2012.

Ju scored his first goal for the club in an FA Cup game against Suwon City on 16 July 2014, which IPark went on to win 3–2 after extra time.

Ju made his debut for the Korean national team on 11 June 2015, appearing as a substitute in a 3–0 victory over UAE.

In May 2018 he was named in South Korea's preliminary 28 man squad for the 2018 FIFA World Cup in Russia.

In the sixth minute of injury time, Ju dispossessed Germany goalkeeper Manuel Neuer inside Korea's half and launched a 75-yard ball forward, which Son Heung-min converted to ensure a famous victory for Korea.