Luongo played for the Australia national team from 2014 until December 2023, making 45 appearances in total before announcing his retirement from international football.

[7] Luongo signed for Tottenham Hotspur in January 2011 after impressing on trial, and went on to make nine appearances for the under-18 team during the 2010–11 Premier Academy League season, scoring three goals.

[9] On 6 February 2012, he was called up to a league match for the first time, remaining an unused substitute as Tottenham earned a goalless draw away to Liverpool.

[10] Thirteen days later he was included in the squad for the last time, again unused in a goalless FA Cup fifth round match away to League One team Stevenage.

[13] Four days later he played his first professional league game, starting in a 1–1 home draw against Blackburn Rovers and making way for Andy Drury after 70 minutes.

[19] He opened the scoring on 4 May in the 70th minute of the first leg of the play-off semi-final against Brentford, but in added time conceded a penalty by fouling Harry Forrester; Kevin O'Connor converted it for a 1–1 draw.

On 28 May 2015, Luongo joined Queens Park Rangers, along with Swindon Town teammate Ben Gladwin, both signing a three-year deal.

[41] On the same day as being released from Middlesbrough, Luongo signed a six-month deal at Ipswich of EFL League One, where he had been loaned to over a decade earlier.

[41] He made his first appearance on 28 January 2023 in the fourth round of the FA Cup, as a 78th-minute substitute for Sam Morsy in a goalless home draw with Championship leaders Burnley;[42] on 18 March, as a starter, he scored the first goal of his spell to conclude a 2–0 win over Shrewsbury Town at Portman Road.

[45] He was selected for the 23-man Australia squad for the 2014 FIFA World Cup in Brazil by manager Ange Postecoglou,[46] but did not feature in any of their three matches as they were eliminated in the group stage.

[47] Swindon teammate Yaser Kasim was also called up for Iraq, meaning that the club would have to compete in their regular League One season without the two central midfielders for a month.

[51] Luongo was named in Australia's 23-man squad for the 2018 FIFA World Cup in Russia by manager Bert van Marwijk after having the most prolific season of his career at QPR.

[55] In October 2024, Luongo returned from international retirement after being named in Tony Popovic's inaugural Australia squad for World Cup qualifiers against China and Japan.