Tseng Chun-hsin (Chinese: 曾俊欣; pinyin: Zēng Jùnxīn; born 8 August 2001), also known as Jason Tseng, is a Taiwanese professional tennis player. He has a career-high singles ranking of world No. 83 by the ATP, achieved on 8 August 2022. Tseng is currently the No. 1 Taiwanese player. He was also the ITF junior No. 1, reaching the ranking after winning the 2018 French Open boys' singles. He is also part of the Chinese Taipei Davis Cup team since 2018, with a win-loss record of 1–0.

Tseng began playing tennis at the age of five with his father, who worked at a night market in Taiwan. He first trained in an elementary school team located in Yonghe District, New Taipei City.

He is nicknamed "the Night Market Champion" (Chinese: 夜市球王) by the Taiwanese media as his parents used to sell tanghulu at the Lehua Night Market in New Taipei City in order to support his tennis career.

He continued his training at the Mouratoglou Tennis Academy in France from age 13 to 17. During that period, he won singles title at the Petits As in 2015.

In 2018, He won his first ITF Futures event in Vietnam. He won the boys' singles title at the French Open and claimed the Wimbledon boys' singles title in the following month.

He made his ATP debut at the 2019 Miami Open as a wildcard.

In the 2019 Summer Universiade, Tseng won the gold medal in men's singles.

In December 2021, Tseng won his first ATP Challenger title in Maia, Portugal. He made his debut in the top 200 at world No. 188 on 20 December 2021.