In April 2009, he was named in the preliminary 25-man squad to represent Queensland in the opening State of Origin match for 2009.[7] He did not make an appearance for the Maroons until the 3rd game of the series though. At the end of the 2009 season Shillington was selected as part of the Australian squad that travelled to Europe for the 2009 Four Nations tournament. He made his debut against England. 2009.
For the 2010 ANZAC Test, Shillington was selected to play for Australia as a prop forward in their victory against New Zealand. Shillington was named the winner of the Mal Meninga Medal as the Raiders' player of the year for 2010.[8]
In 2011, Shillington was picked in the Australia V New Zealand test played in Newcastle playing off the Bench, before heading to Great Britain for the 2011 Four Nations tournament in England and Wales. For the first two games (VS New Zealand & England), Shillington played off the bench wearing the number 16,but in the game VS Wales, he will start at prop (number 8).
When Australia played New Zealand in England, Isaac Luke (New Zealand hooker) came in late on Shillington's legs which looked like it would end his Four Nations tournament. He was in doubt played against England at Wembley but did play.
For the 2013 State of Origin series Shillington was selected to play in Game I, but after the Blues' win was not retained for Game II.
Gold Coast Titans and retirement
On 25 June 2015, Shillington signed a 2-year contract with the Gold Coast Titans starting in 2016.[9] Shillington announced his immediate retirement from rugby league on 9 February 2017 due to chronic injuries.[10]