In August 2007, Mattsson became Junior World Champion for the second time after she defeated the Japanese wrestler Fuyuko Mimura in Beijing.

In September the same year, she competed at her first ever World Championship at senior level in Baku, Azerbaijan, where she placed 8th, assuring herself qualification for the 2008 Summer Olympics.

In April 2008 the young Swedish wrestler won a silver medal at her second ever European Championship at senior level.

[2] In June 2015, she competed in the inaugural European Games, for Sweden in wrestling, more specifically, the women's freestyle 55 kg division.

She won the bronze medal in 53 kg (featherweight) at the 2016 Olympic Games in Rio de Janeiro.