Initially, "Shiftwork" first charted as an album cut by receiving unsolicited airplay that brought the song up to number 42 on the country music charts prior to its official release to country radio. Before the song was officially released, it was credited to both Chesney and Strait. However, once it was officially released as a single, Strait's name was removed from the song due to contractual agreements between his label (MCA Nashville) and Chesney's label (BNA Records). Starting with the Billboard chart dated February 9, 2008, the song was once again billed as the "Kenny Chesney duet with George Strait".
The song is a moderate up-tempo, backed by percussion (mainly steel drums), in which the central characters (Chesney and Strait) express their frustration with constantly working shifts at a convenience store ("Workin' seven to three / Three to eleven / Eleven to seven"). Both characters point out that their job is "a bunch of shiftwork". In the second verse, Chesney talks about taking a trip to the beach to party "from seven to three / Three to eleven / Eleven to seven."
Allmusic critic Stephen Thomas Erlewine considered the song a highlight on Chesney's album, making note of how Strait and Chesney both "playfully soften the F in the title, making for a genuinely funny highlight" (thus making the line sound closer to "shit work"). Brady Vercher of Engine 145 gave it a thumbs-down rating, saying "What makes this a bad song is that it’s dull and boring, with zero redeeming qualities. If music is supposed to make you feel something, then this song captures the monotony of 'shiftwork,' but who in their right mind is going to want to be bored when they listen to a song?" Kevin John Coyne, reviewing the song for Country Universe, gave it a B- rating. He said that " the ’big ol’ pile of shiiiiiftwork” wordplay in the chorus is funny. It doesn’t hold up much on repeated listenings, however." He goes on to say that the song still manages to become a song about getting drunk in the islands.