Sometimes compared to former Australian halfback George Gregan, Genia is pound for pound one of the strongest players in the Wallabies team, able to bench press 172 kg.
In 2013, former All Black scrum-half Justin Marshall said that Genia was the "best in the world for his position".
Genia was born in Port Moresby, Papua New Guinea. He was introduced to rugby union when he moved to Brisbane, Australia at the age of 12 for his secondary education at Brisbane Boys' College, boarding at the school from 2000 to 2005. Genia played rugby for the Australia 'A' Schoolboys team in 2005, and was part of the Australian Under 19 rugby team that won the IRB World Championship in 2006.
Genia's Papua New Guinean father, Kilroy Genia, is a former Cabinet Minister in the Papua New Guinean government. His Australian mother, Elizabeth Genia, was appointed assistant governor at the Bank of Papua New Guinea in 2011. His older brother, Frankie Genia, plays international rugby for the PNG Pukpuks.
Genia was recruited to the Queensland Reds from the GPS club at the end of 2006 before their tour to Japan and obtained his first state cap for the Reds playing against Japan.
Genia made his Super 14 debut for the Reds as a 19-year-old against the Hurricanes at Suncorp Stadium in Brisbane on 3 February 2007. He shared the scrum half position with starting halfback Nic Berry for most of the season, appearing in 11 of 13 matches for the Reds during the season. Later in 2007, Genia played for the Ballymore Tornadoes in the Australian Rugby Championship, appearing in all 8 games played by the team for the year.
In 2008, Genia added a further seven Super Rugby Caps (although only one starting) for the Reds. He was selected as the first choice scrumhalf for the Australian Under 20 team for the 2008 IRB Junior World Cup in Wales.
He played in eight Super Rugby matches in 2009, half of which were starting appearances, and scored four tries during the tournament but missed Queensland's final two matches of the season due to an injured finger tendon.
Genia was selected in the Wallabies squad for the 2009 Tri Nations and made his test debut against the All Blacks at Eden Park in Auckland on 18 July 2009. He came off the bench in the first four matches before getting starting berths against the Springboks in Brisbane, and against the All Blacks in Wellington. Genia then started in all five Tests of Australia's Spring Tour of Japan and Europe, before staying on at the tour's end to help the Barbarians beat the All Blacks at Twickenham.
In 2010, Genia captained the Reds, after regular captain James Horwill suffered an injury in the second match of the season. At the end of the season Genia was voted by his teammates as the 2010 players' player of the year and he won the Pilecki Medal. He was also voted the fans' player of the year, winning the People's Choice award.
Genia won the Pilecki Medal again in 2011, and was voted the Australian Super Rugby Player of the Year by Australian rugby writers. He became the 78th Test captain of the Wallabies when he led the side against the United States at the 2011 Rugby World Cup. He was one of two Australian nominees, alongside David Pocock, for the 2011 IRB Player of the Year award.
In April 2012, he signed a new three-year deal with the Reds after turning down a lucrative offer from the Force. In early September Genia suffered a knee injury in Australia's win over South Africa. Genia missed eight Tests in a row and didn’t expect to return to domestic action until the Reds play the Bulls in Brisbane on 23 March 2013.
It was rumoured that Genia was leaving Australia after the 2015 Rugby World Cup, possibly going to the English Club Bath, but he left Australia at the start of the 2015-16 season to play for Stade Français.
On 15 August 2017, Genia signed with the Melbourne Rebels for the 2018 and 2019 Super Rugby seasons.
Genia is an ambassador for The Kokoda Track Foundation.Queensland Reds
Super Rugby: winner 2011
Tri-Nations: winner 2011
The Rugby Championship: winner 2015