He trained with the Glen Mills-coached Racers Track Club, alongside Usain Bolt and Yohan Blake.

He was a hurdles finalist at the 2007 Pan American Junior Athletics Championships and a silver medallist at the 2008 CARIFTA Games,[4] where he also shared in the 4×100 metres relay gold medal.

[4] Weir began to emerge as a 200 m specialist in 2011 after joining the Racers Track Club under coach Glen Mills.

Later in the 2013 Jamaican National Championships, Weir cruised to the finish line in the 200m final in 19.79 seconds, tying Bolt's world leading mark at that point.

[citation needed] He is known for saying "No English, straight Patois," sparking calls on social networks for T-shirts to be printed with the phrase.

[14] In August 2017 Weir announced his retirement from competition via his Instagram account, after not advancing from the heats in the 200m at the 2017 World Championships in Athletics in London.

[15] In a change of sport, Weir was a member of the Jamaica rugby sevens team that came third at the 2018 Central American and Caribbean Games.