Devlin began his Sheffield United career working under Steve Thompson, his last manager at Notts County. He made a string of substitute appearances before his full debut on 13 April in a 1–1 draw away to Swindon Town, and scored his first goal in a 3–3 draw at Tranmere Rovers. He was cup-tied for the team's run to the FA Cup semi-final, but started both legs of the play-offs, in which they lost to Sunderland on aggregate after Lionel Perez made a "truly world-class save to thwart Paul Devlin's piledriver from " before recovering to save a follow-up header.