"In the Morning" received mixed reviews from music critics who found it reminiscent of Up All Night but were put off by Johnny Borrell's performance. Paul Stokes of NME praised the song's instrumentation and lyricism for its depiction of a hangover after a big party, saying that it "sets the tone for Razorlight to sound like the classic rock’n’roll band they always imagined in their heads: bigger, bolder, brighter." Noel Murray of The A.V.
Club praised the song alongside "Before I Fall To Pieces" for being "large, admirably well-constructed guitar-pop." Doug Kamin of ARTISTdirect hailed the song as an instant rock anthem classic that "should be blasting from every dorm room this fall." John Murphy of MusicOMH praised the song for acting as a promising opener for the self-titled album because of Borrell's ability to deliver "a memorable chorus and a valedictory, celebratory atmosphere about it."