Kennedy wrote "Outnumbered" back in early 2018 with:
Songwriter Jay Mooncie, who is a frequent collaborator of UK singer-songwriter Col3trane.
American songwriter Scott Harris, who is one of Shawn Mendes' go-to songwriting partners. Their collaborations include the Juno single of the year "There's Nothing Holdin' Me Back
Canadian songwriter Stephen "Koz" Kozmeniuk, who also produced the track. His other credits include Kendrick Lamar's Pimp The Butterfly
track "The Blacker the Berry
" and Mark Ronson's "Late Night Feelings