He represented Border at primary school level, playing for their Under-13 side at the Craven Week competition in 2008. He also played for them in the 2011 Under-16 Grant Khomo Week.
After appearing for the Blue Bulls at the Under-18 Craven Week competition in 2013, he was again selected in that season's South African Schools side, playing in their match against France.[4]
In 2014, he was included in the South Africa Under-20 squad for the 2014 IRB Junior World Championship. He started their opening match of the competition, a 61–5 victory over Scotland,[5] and came on as a replacement in their 33–24 win over hosts New Zealand.[6] He didn't feature in their final pool match against Samoa[7] and was an unused replacement in the semi-final win over New Zealand.[8] He also didn't feature in the final, where England won the competition by beating South Africa 21–20.[9]
In the second half of 2014, he played for the Blue Bulls U19 side in the 2014 Under-19 Provincial Championship, making eight appearances – mainly as a flanker – as his side made it all the way to the final against Western Province U19. Nonkontwana started the final, but could not prevent his side suffering a 26–33 defeat.[10]
In 2015, he was again called up to a South Africa Under-20 training squad as preparation for the 2015 World Rugby Under 20 Championship.[11] He started in their friendly match against a Varsity Cup Dream Team XV in April 2015[12] before being named in a squad to tour Argentina for a two-match warmup series.[13] He played in both their 25–22 victory in the first match[14] and their 39–28 victory in the second match against Argentina[15] and was subsequently named in the final squad for the World Championship.[16] He started their first match, a 33–5 win over hosts Italy,[17] but did not feature in their remaining two pool matches or the semi-final defeat to England.[18] He was named on the bench for their third-place play-off match against France, but failed to get any game time.[19]
Blue Bulls
Nonkontwana was named in the Blue Bulls squad for the 2015 Vodacom Cup,[20] but did not make any appearances in the competition.
In June 2015, he extended his contract at the Bulls until October 2017.[21]