Montsho was suspended for two years for an anti-doping rule violation after she tested positive for methylhexaneamine at the 2014 Commonwealth Games.

She ran at the 2008 IAAF World Indoor Championships but did not reach the final after a poor showing in the semifinal.

[5] She defended her continental title by winning the 400 m at the 2010 African Championships in Athletics with a season's best run of 50.03 seconds.

[6] On the 2010 Diamond League circuit, she won at the Bislett Games and was ranked second overall in the 400 m behind Allyson Felix.

Montsho ran her fastest time of the year at the 2010 Continental Cup where, representing Africa, she beat Debbie Dunn to win the gold medal in 49.89 seconds.

[10] She won a gold medal at the 2018 Commonwealth Games in Gold Coast, Queensland, Australia when she and fellow athlete Isaac Makwala made history by being the first athletes from the same country to win both the 400m women and mens in the same Commonwealth Games event.

[12] Subsequently, this finding was confirmed by the results of her 'B' sample which also tested positive for the stimulant methylhexaneamine.