On 18 April 2013, Vaughan re-signed with the Raiders on a 2-year contract to the end of the 2015 season. In Round 7 of the 2013 NRL season, Vaughan made his NRL debut for the Canberra Raiders off the interchange bench against the North Queensland Cowboys in the Raiders 30-12 loss at 1300SMILES Stadium. In Round 14 against the Penrith Panthers, Vaughan scored his first NRL career try in the Raiders 24-12 win at Canberra Stadium. Vaughan finished the 2013 NRL season being named as the Raiders Rookie of the Year, playing in 18 matches and scoring a try in his debut year in the NRL. In October 2013, Vaughan was named in the Italy 24-man squad for the 2013 World Cup, playing in all of their three matches.
2014
In Round 7 against the Melbourne Storm, Vaughan scored a solo effort try in the 79th minute to win the match for the Raiders 24-22 at Canberra Stadium. Vaughan earned selection in the NSW Country team in the City vs Country Origin match off the interchange, scoring a try in the 26-all draw in Dubbo. Vaughan finished the 2014 NRL season with him playing in 23 matches and scoring 7 tries for the Raiders. On 10 September 2014, Vaughan re-signed with the Raiders until the end of the 2017 season.
2015
On 3 May, Vaughan played for New South Wales Country against New South Wales City in the 2015 City vs Country Origin match, playing off the interchange bench in Country's 34-22 win at Wagga Wagga. In Round 20 against the Penrith Panthers, he scored his first career double in the Raiders' 34-24 win at Penrith Stadium. He finished the 2015 season having played in all of the Raiders' 24 matches and scoring 4 tries. On 8 September, he was named in the 2015 Prime Minister's XIII squad but later pulled out due to injury.
2016
On 30 January 2016, Vaughan was named in the Raiders' 2016 NRL Auckland Nines squad. On 8 May 2016, for the third year in a row, Vaughan played for New South Wales Country against New South Wales City, where he played off the interchange bench in the 44-30 loss in Tamworth. After Round 18, Vaughan was dropped to the Raiders NSW Cup team the Mount Pritchard Mounties after Coach Ricky Stuart opted to select the newly arrived prop Junior Paulo from the Parramatta Eels, rising youngster Joseph Tapine and late bloomer rookie Clay Priest to be part of the forwards rotation. But after Clay Priest suffered a season ending ankle injury, Vaughan beat out overlooked veteran forwards Shaun Fensom and Jeff Lima to fill in the vacant spot on the interchange bench for the Finals. Vaughan finished the 2016 NRL season playing 20 matches and scoring 4 tries for the Canberra Raiders. On 15 October 2016, it was announced that Vaughan signed a 3-year contract with the St. George Illawarra Dragons worth $1.75m, starting from 2017 and will see him at the club until 2019.
2017
On 10 February 2017, Vaughan played for the World All Stars against the Indigenous All Stars in the 2017 All Stars match, playing off the interchange bench in the 34-8 loss at Hunter Stadium. In Round 1 of the 2017 NRL season, Vaughan made his club debut for the St George Illawarra Dragons against the Penrith Panthers, starting at prop in the 42-10 win at Jubilee Oval. In his next match in Round 2 against the Parramatta Eels, Vaughan scored his first club try for the Dragons in the 34-16 loss at WIN Stadium. On 13 September, Vaughan was named in the 2017 Prime Minister's XIII squad.
2018
In 2018, Vaughan was named in The NSW Blues squad for The 2018 State of Origin series. Vaughan also had the honour of being the 1000th player to pull on a Blues jersey. On 5 June 2018, Vaughan told The Sydney Morning Herald that "The best thing I did in my career was to leave Canberra and go to St George Illawarra". Vaughan went on to play in all 3 games of 2018 State of Origin series as The Blues won the shield 2-1.
2019
After a good start to the 2019 NRL season, Vaughan was selected to play for New South Wales in the 2019 State of Origin series. Vaughan played in all 3 games and scored a try in the deciding match which was played at ANZ Stadium. The Blues won 26-20 courtesy of a last minute try to James Tedesco. New South Wales would go on to win the series 2-1 and retain the shield for the first time since 2005. Vaughan made a total of 23 appearances for St George in the 2019 NRL season as they endured one of their worst ever seasons finishing 15th on the table above the last placed Gold Coast. St George had gone into the season as one of the club's expected to make the finals and challenge for the premiership. On 30 September, Vaughan was named at prop in the Australia PM XIII side. On 7 October, Vaughan was named in the Australian side for the upcoming Oceania Cup fixtures.
