The song was written by Mendes, Scott Harris, Mike Sabath, and Eddie Benjamin.

Mendes first announced "It'll Be Okay" alongside the single's cover art and a snippet on November 30, 2021, setting its release date for the following day at 7:00 P.M. EST.

[3] In the pre-chorus, Mendes expresses that he cannot live without his significant other after the split, which therefore has him assuring himself that it will all be alright soon: "I start to imagine a world where we don't collide / It's making me sick, but we'll heal and the sun will rise".

[5] Further on, in the second verse, he sings about what went to waste after the relationship ended: "Oh, the future we dreamed of / Is fading to black, oh / And, oh, there's nothing more painful".

[6] The music video depicts Mendes walking through the streets of Toronto at night as snow falls around him.