The 31st round draft pick of the Cincinnati Reds in 2017, Bremner was a member of the U-18 Canadian Baseball Junior National Team from 2015-2017. The team placed fourth in the world at the 2017 U-18 Baseball World Cup. He won silver with the Toronto Baseball Association at the Ontario Summer Games. Bremner played in the Bantam Nationals for the Vaughn Vikings in 2015, and was named All-Tournament Shortstop, MVP for the team and won the batting title. He has also played for the Toronto Mets. At the University of Cincinnati in 2018, he clubbed 4 doubles and scored 17 runs in 104 plate appearances.