Tseng began playing tennis at the age of five with his father, who worked at a night market in Taiwan.

[3][4] He first trained in an elementary school team located in Yonghe District, New Taipei City.

[15][16] The following month in February 2022, Tseng won his second ATP Challenger title in Bangalore, India.

He qualified for his second Grand Slam tournament at the 2022 French Open to make his debut at this major.

[19] He lost in the first round in five sets in a match that lasted 4 hours 23 minutes against João Sousa.

[citation needed] He qualified for the main draw and defeated Alexander Shevchenko on his debut at this tournament, recording his first Masters win.

159, he entered the second round of the main draw at the Croatia Open as a lucky loser replacing third seed Holger Rune and defeated Fabio Fognini to reach his first ATP Tour quarterfinal.

[25][26] Three weeks later he reached the final at the 2024 San Marino Open, losing to Alexandre Müller in a deciding set tiebreak.