|Date of birth||18 June 1994|
|Place of birth||Brisbane, Queensland, Australia|
|Height||1.85 m (6 ft 1 in) |
|Weight||101 kg (15 st 13 lb; 223 lb) |
|School||St Joseph's College, Nudgee|
|Rugby union career|
McMahon was born and raised in Brisbane and took his first steps in senior rugby with GPS in the Queensland Premier Rugby competition. He played in the side which was runner-up in the 2013 competition and featured alongside future Rebels team-mates Colby Faingaa and Bryce Hegarty. McMahon's displays saw him named as a member of the Melbourne Rebels extended playing squad for the 2014 Super Rugby season. He was surprisingly named in the number 6 jersey for the Rebels season opener against the Cheetahs at AAMI Park on 28 February 2014. McMahon played the whole 80 minutes in a 35–14 victory for the home side.
On 16 April 2014, the Melbourne Rebels announced that McMahon signed a new two-year deal, running until the end of 2016. McMahon is also an avid golfer and a 5 handicap.
McMahon represented Australia Schoolboys in 2011, at the age of 17, before becoming the youngest ever player to play for the Australia Sevens team in 2011, going on to feature for the side for another two years whilst also making the Australia Under-20 squad for the 2012 IRB Junior World Championship in South Africa. In May 2014, he was named to captain Australia in the 2014 IRB Junior World Championship, to commence in Auckland in June. This followed his strong performances with the Australian Sevens and the Melbourne Rebels.
On 22 October 2014, McMahon was named in the Australian national team for the Wallabies 2014 End-of-year test, under the new coach of Michael Cheika. He made his first appearance against the Barbarians on 1 November, but it was a week later he made his test debut against Wales at the Millennium Stadium, starting in the #6 Jersey.
Super Rugby statistics
- As of 21 July 2016 
- "Sean McMahon Melbourne Rebels Player Profile". Rebels Rugby. Retrieved 2 March 2014.
- "Sean McMahon Player Statistics". itsrugby. Retrieved 2 March 2014.
- "Rebels name Extended Playing Squad (EPS) for 2014". Sanzar Rugby. 26 September 2014. Retrieved 2 March 2014.
- "SA Rugby Match Centre – Rebels 35-14 Toyota Cheetahs". South African Rugby Union. 28 February 2014. Retrieved 15 March 2016.
- "Melbourne Rebel name debutant Sean McMahon at flanker ahead of Super Rugby clash with Cheetahs". ABC. AAP. 27 February 2014. Retrieved 2 March 2014.
- "Rebels Re-Sign Talented Youngster" (Press release). Melbourne Rebels. 16 April 2014. Retrieved 16 April 2014.
- "Sean McMahon - Super Rugby Australia - NewStar Sports". Sean McMahon. Retrieved 24 October 2016.
- "Australian Under 20s squad named for 2012" (Press release). Australian Rugby Union. 2 May 2012. Retrieved 2 March 2014.
- "McMahon leads junior Wallabies". Rugby 365. 5 May 2014. Retrieved 5 May 2014.
- "Australia JWC Squad 2014". IRB. Archived from the original on 5 May 2014. Retrieved 5 May 2014.
- "Australian Under 20s announce squad for Junior World Champs" (Press release). Australian Rugby Union. 5 May 2014. Retrieved 6 May 2014.
- "Tough choices ahead for Michael Cheika after impressive Wallabies rout Uruguay 65-3". www.rugbyworldcup.com. Retrieved 18 October 2015.