North was born in 1992 in King's Lynn. His mother is Welsh and from Anglesey, Wales, and his father is English and from Yorkshire. The family returned to Anglesey when he was aged two and he is a fluent Welsh language speaker. North was educated at Ysgol Uwchradd Bodedern on Anglesey and later at Llandovery College.
North played as a junior for Llangefni, Pwllheli, Rhyl and Gogledd Cymru under-16s.
Up to the point of his international call-up, North had played six matches for the Scarlets first team, a record restricted by an injury.
On 9 April 2013 it was confirmed that North would sign for Northampton Saints in the Aviva Premiership for a reported fee of over £200,000. This announcement followed the Welsh Rugby Union claiming that Scarlets had attempted selling North to French clubs, which they had denied.
He scored his first Northampton Saints try against Sale Sharks after some excellent work by Jamie Elliott to make the score 12–0 in a game that finished 33–14 to Northampton. He scored his first Heineken Cup try for Saints on 14 December against Leinster Rugby.
North hit his 150th point for Saints after scoring a try against Exeter Chiefs in the Aviva Premiership on 30 September 2016.
Most recently North was instrumental in Saints securing a European Rugby Champions Cup place for the 2017/18 season as the side beat both Connacht Rugby and Stade Francais in the European Champions Cup play-off games to claim the final spot in the competition for the following season.
After an impressive start to the 2010 season, in October 2010, he was selected to the 33 man squad for the Autumn international series. On 11 November 2010 North was named in the Wales team to face South Africa on 13 November, making him the joint third youngest player to represent Wales behind Tom Prydie and Norman Biggs and equal to Evan Williams.
North made an impressive start to his international career on 13 November 2010 in a match against the reigning World Champions, by scoring two tries for Wales as they lost to South Africa 29–25 in the Millennium Stadium, Cardiff, Wales. He set a number of Welsh and international records in the match:North, aged 18 years, 214 days, became the youngest player ever to score a try in his debut for Wales. The previous record holder was Tom Pearson, who was aged 18 years, 238 days when he scored against England in 1891.
He also became the youngest player ever to have scored two tries against a major rugby nation, whether on his debut or not. The previous record holder was James O'Connor of Australia, who was aged 18 years, 343 days when he scored a hat-trick against Italy in 2009. (Taylor Paris of Canada turned 18 in October 2010 and scored two tries in his second appearance against Spain on the same day as North's debut, but Spain is also not considered a major rugby nation, although they have qualified for one World Cup.)
Following his international debut at the 2010 end-of-year tests, North soon became a regular fixture for Wales in their starting XV. He was not picked to play for Wales for most of the 2011 Six Nations as coach Warren Gatland generally opted for more experienced wingers Shane Williams and Morgan Stoddart, however during the final weekend of the tournament North was given his opportunity to start on the left wing against France, as Williams was not picked to play and Stoddart was on the replacements bench.
After Morgan Stoddart suffered a broken leg during a world cup warm-up match against England, North was called up as a first-choice winger for Wales for the 2011 Rugby World Cup held in New Zealand. He started on the left wing for Wales' first Pool D match against South Africa, which they narrowly lost by a score of 17–16 against the reigning world champions. North again started on the wing against Samoa and then came on as a replacement in the 55th minute against Namibia, scoring two tries in the latter. He then started against Fiji, scoring a try.
Wales played Ireland in their quarter-final game, where North started (this time on the right wing), with Wales winning by 22 points to 10. They went on to face France in the semi-finals, but lost by a score of 8–9, with North again on the right wing. The match included a controversial moment in the 19th minute where the Welsh captain Sam Warburton was red-carded for a tip-tackle against Vincent Clerc, meaning Wales played the remainder of the game with a one-man disadvantage.
After the world cup, North continued in his place as a regular starter for Wales. His performances during the 2012 and 2013 Six Nations championships were instrumental in the team winning both tournaments, taking the grand slam in 2012 and losing only their opening match against Ireland in 2013. North started every game for Wales in both Six Nations tournaments.
North also played regularly for Wales during the Autumn internationals at the end of each year, where various teams from outside Europe (often the top southern hemisphere nations of New Zealand, Australia, South Africa and Argentina) tour to the UK to play the home nations in official test matches.
He was named as part of the Lions squad for the 2013 British and Irish Lions tour to Australia.
On 22 June 2013 in Brisbane, North scored the first Lions try vs Australia; a run from inside his own 10m line beating 4 players. However, North's celebration was slightly over exuberant and he later apologised, saying he felt 'horrendous' after making a triumphant gesture towards Will Genia. The Lions went on to win the First Test 23–21.
On 29 June 2013, North carried out a 'fireman's lift' manoeuvre on Australia's Israel Folau whilst running with the ball in the Second Test between the Lions and Australia in Melbourne, injuring himself in the process as the Lions went down to a 16–15 defeat.
On 6 July 2013, in Sydney, North scored his fourteenth international Test try and his second Lions Test try as the Lions sealed a 2–1 series win over Australia with a 41–16 victory.
North competed for Wales during the 2014 Six Nations, and started all five matches, including a switch to outside centre against France, with Wales hoping that North's size and strength would make him an adequate opponent against the 19-stone frame of Mathieu Bastareaud, who was starting in the same position for Les Bleus. The plan worked, as Wales won 27–6, with North scoring a try after 5 minutes of play.
North played 4 out of 5 games for Wales during the 2015 Six Nations, only missing the match against Scotland in the second round, due to a concussion he suffered against England in their first round match.
For the 2015 Rugby World Cup, Wales found themselves in Pool A. North played in all but one of Wales' pool matches.
Wales advanced to the quarter-finals to face South Africa at Twickenham, where North started on the left wing.
North played for Wales during the 2016 Six Nations, scoring tries against Scotland, France, England and Italy.
The winger was selected in the Wales squad for the Autumn Internationals and after Premiership Rugby decided to allow Welsh players to be selected for the opening test on 5 November 2016, despite that falling outside the designated International window, earned his 63rd cap for Wales against Australia on that day.
It was announced that North would travel to New Zealand with fellow Northampton Saints Courtney Lawes as the pair linked up with the British and Irish Lions for their tour of the Southern hemisphere country.
North's long-term girlfriend is British Olympic cyclist Becky James.