Chris Wilder has made his third signing of the summer with Enda Stevens agreeing to join on a three year deal.
Defender Stevens, 26, who has just helped Portsmouth to the Sky Bet League Two title, is out of contract this summer and has committed his immediate future to the Blades, his deal will commence on 1st July.
Boss Wilder commented: "We had Enda at Northampton on loan and it was clear he needed to play regular football. He's done that over the last couple of years and picked up a few honours at Portsmouth. He is an attacking full-back and the way we play, the wide areas are important - Enda provides us with extra options. He is a good age and has designs to play international football."
Enda added: "I'm delighted the paperwork has been done early, it gives me the chance to settle in and concentrate on my football as soon as we report back for pre-season training. I enjoyed working under the gaffer for a short spell at Northampton and how he plays the game is similar to the approach at Portsmouth so hopefully it will be a smooth transition."
The Irishman represented Cherry Orchard, UCD, St Patrick's Athletic and Shamrock Rovers, playing in the UEFA Europa League, before moving to England with Aston Villa in August 2011. First team opportunities at Villa Park were limited and Stevens moved out on-loan to gain first-team football, with Notts County, Doncaster Rovers (twice) and Northampton Town his destinations.
In June 2015 the left-back joined Portsmouth on a two-year deal and during his time at Fratton Park he amassed nearly 100 appearances under Paul Cook, signing off by winning the League Two title earlier this month.
Stevens is the third capture to bolster Wilder's squad ahead of next season's Sky Bet Championship campaign after the signatures of Ched Evans and Nathan Thomas were confirmed earlier this month.