From the age of six, she continued her exercises under the supervision of aerobics gymnastics trainer Gürkan Er at Manisa Celal Bayar University.

[1][3] At the 2016 Aerobic Gymnastics World Championships in Incheon, South Korea, she won the gold medal in the Junior Women's Individual event.

[1][7] Onbaşı returned with three gold medals in total from the 2nd Mediterranean Championships 2017 in Guadalajara, Spain, and the 7th International Open Competition 2017 in Cantanhede, Portugal.

[3][4] She captured another gold medal in the Junior Women's Individual event at the 2017 Aerobic Gymnastics European Championships in Ancona, Italy.

[4] She earned a bronze medal in the Junior Women's Individual event at the 2018 Aerobic Gymnastics World Championships in Guimarães, Portugal.