Dellavedova competed for the Australian junior national team at the 2009 FIBA Under-19 World Championship. He was the team's third leading scorer – averaging 10.1 points per game – for the fourth-place Australians. He was named in the Australian senior national team, the Boomers, to compete for the first time at the 2009 FIBA Oceania Championship. At age 19, he was the youngest Australian player at the competition. He went on to compete for the Boomers at the 2012 London Olympics, the 2014 World Cup in Spain, the 2016 Rio Olympics, and the 2019 World Cup in China.