Stephen M. Deusner of Engine 145 gave the song a thumbs-down. Although he described the lyrics favorably by saying that "the scenario is all the more affecting for its mundanity" and "'Do I' implies no hint of a happily ever after, and that ambiguity gives the lyrics extra impact", Deusner criticized Bryan's vocal performance, saying "it never quite conveys much desperation or despair. There’s no worry in his voice, nor does it sound like he’s trying to keep a stoic front." Chris Neal of Country Weekly described the song favorably in his review of the album, saying that it "shows a knack for convincingly delivering hymns to thwarted love."
"Do I" debuted on the U.S. BillboardHot Country Songs chart at number 53 for the chart week of May 9, 2009. In November 2009, the song became his first Top 40 on the Billboard Hot 100. The song has sold 1,605,000 copies in the U.S. as of August 2015.