[1] He was selected to the international squad at the age of 19,[2] due to his fast bowling capabilities of 140+kmp/h and excellent performances in the Under-19 team.
[12] Prior to his debut, Kumara was part of Sri Lanka's squad for the 2016 Under-19 Cricket World Cup.
[13] He guided the Sri Lanka U-19s team through to the semi-final along with pacer Asitha Fernando to win the match by six wickets.
[22][23] In August 2018, he was named in Sri Lanka's squad for the one-off Twenty20 International (T20I) match against South Africa, but he did not play.
[24] In November 2018, Kumara was removed from Sri Lanka's Test squad for their series against England due to disciplinary reasons.
[28] In September 2021, Kumara was named as one of four reserve players in Sri Lanka's squad for the 2021 ICC Men's T20 World Cup.