Junior Jang started playing international matches from the South Korean cadet boys' team in 2009 – Bahrain Junior Open held in
Manama,
Bahrain. He won boys' singles title at the
2013 World Junior Table Tennis Championships.
2018 He won the gold medal in
2018 Korea Open held at
Daejeon,
South Korea without even having been a seeded player at the start of the tournament. He became the first-ever ITTF World Tour triple crown winner in this event as well by also winning gold medals in men's doubles and mixed doubles. In March, Jang played in the WTT Star Contender event at WTT Doha, but he suffered a disappointing round of 32 exit to
Ruwen Filus. Jang lost 4–3 to
Hugo Calderano in the round of 16 in the men's singles event in the Tokyo Olympics. ==Singles titles==