[2] De Klerk was included in the Lions squad for the 2014 Super Rugby season[3] and made his debut in a 21–20 victory over the Cheetahs in Bloemfontein.

[9][10] De Klerk was rewarded for his Super Rugby form when he was selected by the then recently appointed Springbok coach Allister Coetzee in South Africa's 31-man squad for their 2016 three-test match series against Ireland[11] and made his test debut as the starting scrum-half in the opening test at Newlands Stadium.

After signing for Sale Sharks in 2017, De Klerk was ineligible to represent the Springboks due to having fewer than 30 caps.

[12] However, after this selection criterion was abolished in 2018, new Springbok coach Rassie Erasmus recalled De Klerk to the team for the 2018 three-test match series against England.

[14] He was a key player for South Africa's World Cup victory, being named as the starting scrum-half in two of their pool matches, as well as all their play-off games.