The following season, however, after another injury to Irwin in the team's home opener in the spring, Bono was once again promoted to the starting line-up, and subsequently cemented his place as the team's outright first-choice shot-stopper by September 2017, also establishing himself as one of the best goalkeepers in the league: he broke the club's record for most clean sheets by a goalkeeper in a single season (10), and overall he kept the second highest number of clean sheets in the league season behind Stefan Frei, and won more games than any other MLS goalkeeper that season (19), while he also surpassed Frei's mark for most career MLS wins by a Toronto FC goalkeeper; furthermore, he produced 72 saves and had a 69.2 per cent save percentage, averaging 1.12 goals against per game. In the post-season, Bono's performances once again proved to be decisive in his team's Playoff run, as he conceded two goals and made eight saves en route to the MLS Cup Final, keeping clean sheets in both legs of the Eastern Conference Final against Columbus Crew. On December 9, 2017 he kept a clean sheet in a 2–0 win over Seattle Sounders in the 2017 MLS Cup Final at BMO Field – a rematch of the previous season's final –, which saw Toronto complete an unprecedented treble of the MLS Cup, the Supporters' Shield, and the Canadian Championship.