Jutamas Jitpong lost to Turkey's Buse Naz Cakiroglu on Sunday in her quarter-final bouts in the women's flyweight (51kg) division at the Tokyo Games.
The Thai fighter lost 5-0 to Cakiroglu, who was the 2019 world championship's silver medallist and the winner of the European championship that year.
The loss ended her bid for glory in the Games.
Another boxer, Chatchai-decha Butdee, on Sunday faces three-time world champion Lazaro Alvarez of Cuba in the men's featherweight (57kg) division,
Chatchai-decha needs a win to be assured of at least a bronze medal.