 Brault-Guillard made his international debut for Canada on October 16, 2018, coming on as a substitute in the 66th minute for Liam Millar in the 2019–20 CONCACAF Nations League qualifying match against Dominica.The match finished as a 5–0 home win for Canada.He was named to the final 23-man squad for the 2019 CONCACAF Gold Cup on May 30, 2019.