Upon the team's return, he was named in the final squad for the 2015 World Rugby Under 20 Championship. He played in all three of their matches in Pool B of the competition; he played off the bench in a 33–5 win against hosts Italy, before starting both their 40–8 win against Samoa and their 46–13 win over Australia. Jenkins also scored a try in each of the two matches that he started to help South Africa finish top of Pool B to qualify for the semi-finals with the best record pool stage of all the teams in the competition. He started their semi-final match against England, but could not prevent them losing 20–28 to be eliminated from the competition by England for the second year in succession. He started their third-place play-off match against France, scoring his third try of the competition to help South Africa to a 31–18 win to win the bronze medal.