He played Tier II Junior "A" hockey with the Longueuil Rebels and, undrafted, turned pro with the Beauce Jaros in 1975-76. There he caught the eye of the Quebec Nordiques, then in the World Hockey Association (WHA) and was signed by them. Weir was a regular for the Nordiques from 1976 on, winning the Avco World Trophy with them in 1976-77. After missing much of the 1977-78 season due to injury, Weir was a defensive fixture on the Nords through their WHA years and into the National Hockey League in 1979. Weir retired in 1986.