Amateur career Weir was educated at
Cathkin High School. He played for
Cambuslang RFC. Weir was drafted to
Glasgow Hawks for the 2010–11 and 2011-12 seasons. Drafting meant he could play for an amateur side when not used by his professional club. Weir was drafted to
Aberdeen GSFP for the 2012-13 season; and
Stirling County for the 2013-14 season. In the 2014-15 season, Weir was drafted to
Currie; at the time Currie - an Edinburgh club - was nominally under Glasgow Warriors' purview. Weir's move to Edinburgh Rugby meant that he was then drafted to amateur clubs under Edinburgh's purview instead. So Weir was drafted to
Hawick in 2016-17; and then
Boroughmuir for season 2017-18.
Professional career Weir made his professional competitive debut for
Glasgow Warriors on 23 April 2010 against
Leinster Rugby at
Firhill Stadium in the
Celtic League, becoming
Glasgow Warrior No. 181. In March 2014, Weir signed a new two-year contract with Glasgow Warriors. He won the
Pro12 title with Glasgow in season 2014-15. On 24 January 2016, Weir left Glasgow to join
1872 Cup rivals
Edinburgh on a two-year deal from the 2016-17 season. After racking up 221 points in 30 games during his time at BT Murrayfield Stadium, he left Edinburgh to join English side
Worcester Warriors in the
Premiership Rugby on a one-year deal. Weir continued to perform at Worcester and in December 2018, he signed a new two-year extension with the club. On 13 January 2021, Weir returned home to Scotland to re-join
Glasgow Warriors which started his professional career ahead of the 2021-22 season. He ended his professional playing career on 3 January 2026, playing for
Glasgow Warriors against Zebre in the United Rugby Championship. In a 7 try win over the Italian side, Weir scored a try and 3 conversions, coming off the bench and winning the man of the match, dislocating his finger and tearing his hamstring in the process. At the time of his retirement he was the first and only Glasgow Warrior to play in two championship winning sides for the club, and was the club's third highest points scorer. He played 163 times for the Glasgow side, scoring 967 points in the process.
International career Weir was reserve Fly-Half for Scotland's 2013 Six Nations campaign but with Scotland failing to score tries, Weir's Glasgow teammate Ruaridh Jackson was dropped and Weir stepped in. He started Scotland's final two games in the Championship which Scotland finished in third place. Weir was starting fly-half for Scotland's 2014 Six Nations having impressed in Glasgow's successful season. He scored a last minute Drop-goal to beat Italy in Rome for the first time since 2006. Weir received a call-up to the
Scotland squad for the
2017 Six Nations Championship. Weir was called up to Scotland’s extended Six Nations squad in 2019 after an outstanding first season with Worcester Warriors. His consistent form coupled with Scotland’s decision to suspend
Finn Russell for a breach of team protocols led to another recall ahead of the 2020 Six Nations.
Coaching career In 2026, Duncan Weir was announced as a new
Glasgow Warriors academy coach along with
Shade Munro and Nick Ryan. Weir said "We want to graduate as many of our academy players to the pro game as possible – that’s my goal in the new position, and seeing young backs go from the academy to long and decorated careers for Glasgow Warriors and Scotland would be something that would fill me with great pride." ==References==