He was selected in the 31-man Ireland squad for the 2019 Rugby World Cup, having featured in the warm-up match against Italy, though an ankle injury prevented Carbery from taking any further part in the warm-up matches. He returned from the injury to make his Rugby World Cup debut off the bench in Ireland's shock 19–12 defeat against hosts Japan on 28 September 2019, before providing scrum-half cover from the bench in the 35–0 win against Russia, and featuring off the bench in the 47–5 win against Samoa and the 46–14 quarter-final defeat against New Zealand. A wrist injury sustained whilst on provincial duty with Munster ruled Carbery out of the 2020 Six Nations Championship, and surgery for the ankle injury he sustained during the world cup ruled him out of the tour of Australia in July 2020.