[4] He won the Eddie Herr International and Junior Orange Bowl Boys under-12s titles in December 2008, and was subsequently signed, along with his brother Chung Hong, to the Nick Bollettieri Tennis Academy at IMG in Florida.

[5] He began competing on the ITF junior tour in 2012, and was runner-up in the 2013 Wimbledon Boys' Singles, a month after winning his first Futures title.

[4] He competed in the qualifying for the 2014 US Open and won two matches for the South Korea Davis Cup team to help keep them in the Asia/Oceania Zone Group I.

[4] Chung reached the final qualifying round for the Australian Open, but focused his efforts on the Challenger Tour.

[10] His rapid rise up the rankings and an error on behalf of the Korean Tennis Federation meant that he missed the entry deadline for the 2015 French Open.

In the 2015 Wimbledon Championships, he reached his first main draw in a Grand Slam tournament, losing in five sets in the first round to Pierre-Hugues Herbert.

In April, Chung reached the quarterfinals of the 2017 Barcelona Open Banco Sabadell, taking Rafael Nadal to a tie-break before eventually losing.

To reach the quarterfinals, Chung came through qualifying and the main draw to record six wins in a row without dropping a set, including victories over Denis Istomin, Phillip Kohlschreiber and Alexander Zverev.

Chung picked up his first big result of the year by reaching the quarterfinals of the Auckland Open, recording a win over John Isner in the second round.

At the Australian Open, Chung made his breakthrough into the limelight by becoming the first South Korean player, male or female, to advance past the fourth round of a Grand Slam tournament.

[17] In the next round, Chung won a straight sets match against six-time Australian Open champion and former world number one Novak Djokovic, who had just returned from injury.

[21] The Korean also played the doubles event with Radu Albot and defeated the defending champions Henri Kontinen and John Peers.

He then played in the Mexican Open, where he defeated Donald Young and Ernesto Escobedo before losing to Kevin Anderson in straight sets.

At Indian Wells, Chung beat Dušan Lajović, Tomas Berdych and Pablo Cuevas to advance to his maiden Masters quarterfinals appearance, but lost to Roger Federer in straight sets.

At Miami, Chung defeated Matthew Ebden, Michael Mmoh, and João Sousa, reaching the quarterfinals where he lost in straight sets to John Isner, who went on to win the tournament.

[23] After two years of absence from the ATP tour he came back to play doubles with compatriot Kwon Soonwoo at the 2022 Korea Open.

[24][25][26] They won their first round match against Hans Hach Verdugo and Treat Huey in three sets and second against fourth seeds André Göransson and Ben McLachlan.