Yaroslava Mahuchikh started the high jump at the age of 13, but she was able to improve significantly in two years. At the age of 15, she won the gold medal at the 2017 IAAF World U18 Championships in Nairobi by the largest margin in World U18 Championships history with her personal best of 1.92 m. She equalled the championship record of her compatriot Iryna Kovalenko from 2003 and set an unofficial World record for a 15-year-old. A few weeks later she won the high jump event at the 2017 European Youth Olympic Festival in Győr with a clearance of 1.89 m.