Blake was selected by
Philadelphia Union first overall in the
2014 MLS SuperDraft. Originally anticipated to be the Union's starting goalkeeper, he was deputized to the bench when the Union signed designated player
Raïs M'Bolhi. Blake made his first appearance for the Union in a friendly match against
Crystal Palace in July 2014. He made his first competitive start for the Union in a 1–0 win against
Montreal Impact, who debuted
Didier Drogba as their new designated player. Blake started for five of the remaining eight matches in the
2015 season. On 26 September 2015, playing against
New England Revolution, Blake set a Union team record for saves in a match with 10 stops to preserve a 1–1 draw. During the
2016 season, Blake cemented himself as the clear starting goalkeeper for the Union. In July 2016, he was included in the roster for the
2016 MLS All-Star Game. He was also selected to the
2019 MLS All-Star Game as the Union's only representative. in 2017. During the
2020 season, Blake earned accolades for his performances including the Golden Glove for the
MLS is Back Tournament, his second
MLS Goalkeeper of the Year award, and second selection to the
MLS Best XI. Blake posted a 77.8 save percentage and allowed only 18 goals, leading the league in both stats for goalkeepers with 20 or more appearances. He also led the league in wins (13) and posted eight clean sheets. In July 2021, Blake signed a contract extension with the Union through the 2024 season, with a club option for 2025. In August, Blake was announced as a selection to the
2021 MLS All-Star Game versus the
Liga MX All-Stars. in 2025. ==International career==