[2] Ema Kapustová made her international debut at the 2019 Youth World Championships in Osrblie, achieving a 21st place as her best result.

However, she won a bronze medal at the Youth World Championships in Obertilliach and improved from 30th to 9th place in the pursuit event.

She made her World Cup debut in Östersund in the winter of 2023/24 and achieved her first pursuit competition after finishing 56th in the sprint in Hochfilzen.

She notably improved her performance in Lenzerheide, finishing 41st in the sprint and 28th in the pursuit, earning her first World Cup points.

Kapustová won her first medal in the senior category at the European Championships in Slovakia on January 24, 2024, finishing with the third-best time in the individual race.