The 2019 Toronto Defiant season was the first season of Toronto Defiant's existence in the Overwatch League as one of eight expansion franchises added for the 2019 season. After posting a 5–2 record in Stage 1, the Defiant qualified for the Stage 1 Playoffs, but a 0–3 loss against the Shock eliminated the team in the quarterfinals. The team failed to recreate the success they found in Stage 1 in the following stages, going 2–5, 0–7, and 1–6 in Stages 2, 3, and 4, respectively. A 2–3 loss to the Fusion on August 4 officially eliminated Toronto from postseason contention, and three days later, the team released head coach Lee "Bishop" Beom-joon. Despite numerous roster changes throughout the season, the Defiant finished the season in 17th place overall with an 8–20 record.

Toronto Defiant is a Canadian professional Overwatch esports team based in Toronto which currently participates in the Overwatch Champions Series. Founded in 2018 as an expansion team for the Overwatch League (OWL), Toronto began play in 2019 and was one of two OWL teams based in Canada. The team is owned by OverActive Media, who also owned the Montreal Rebellion, a former academy team for the Defiant that competed in Overwatch Contenders (OWC).