For Mendes' second performance, the singer strapped on his guitar trotted out hit Hot 100 Top 10 hit "Treat You Better."
"Never been so emotionally consumed in a song in my life. Thank you @nbcsnl. Thank you guys for getting me here," Mendes tweeted following the performances.
In an interview with Rolling Stone in April, Mendes admitted his rise to stardom has overwhelmed him in ways.
"Even to this point, I don't feel like I'm caught up talent-wise to my career," Mendes said."I never felt like I was good enough and, only nowadays, am I starting to feel like I deserve [all this]. I felt like there were so many talented people who should be getting what I have."
After concluding his Shawn Mendes World Tour in November, the singer will embark on his Illuminate World Tour in March, with North American dates kicking off in July.