On September 11, 2016, Kwiatkowski won the American Collegiate Invitational, which earned him a wild card into the qualifying tournament for the 2017 US Open.

[6] Other notable college achievements:[7] After winning the NCAA singles championship, Kwiatkowski was awarded a wildcard into the main draw of the 2017 US Open.

[10] He was also awarded a wildcard into the main draw of the 2020 US Open,[11] where he lost in the first round to Kwon Soon-woo in four sets.

[3] On 23 February 2021, Thai-Son Kwiatkowski successfully obtained Vietnamese citizenship in order to play for Vietnam's national tennis team in upcoming tournaments.

[16] He is playing for Hung Thinh – Ho Chi Minh City team since October 2019.