A sleeper hit, it gained traction on the video-sharing app TikTok in late 2020 and became SoFaygo's breakthrough song.

[3] In regard to composing the song, SoFaygo stated: Writing-wise, production-wise, we just killed that shit.

I didn't really realize how good of a song it was like at the time until it really aged and I really paid attention to how people reacted to it.

[5][6] DJ Booth commented on the song, "Faygo sings every line of 'Knock Knock' with the confidence and clarity of a pop star, but, like so many of the scene's creations, his vocals feel stitched together, rough around the edges.

The beat, too, has that handmade quality—a see-sawing MIDI orchestra courtesy of Lil Tecca, an underrated producer whose credits run rampant through Faygo's corner of online rap.