Chris Wilder has bolstered his defensive options with the signing of a proven Championship defender.
Jack Robinson of Nottingham Forest becomes United's second signing of the January transfer window, penning a two-and-a-half-year deal at Bramall Lane, with the Blades paying an undisclosed fee for his services.
Speaking of the signing of Robinson, boss Wilder remarked: "Jack's got a great pedigree and he will make our squad stronger.
"But he isn't just coming in to make the numbers up, it's a specific position in our system and we feel he is the best option for us at this time.
"Jack can comfortably play in a couple of roles and we're delighted to add him to the group. He's got a fantastic attitude and he's ambitious to earn a place in the team."
Warrington-born Robinson is the second youngest player to have played for Liverpool, making his debut aged 16 years and 250 days.
During his time at Anfield, Robinson made three league appearances, but furthered his development with loan spells at Wolves and Blackpool, starting 33 times in the Championship whilst at Bloomfield Road.
In August 2014, the versatile operator joined QPR, but spent the 2014/15 campaign at Huddersfield Town where he made 30 league appearances, prior to returning to Loftus Road.
Robinson went on to feature over 40 times for the R's, before joining Nottingham Forest in the summer of 2018. The 26-year-old has remained a regular in his time at the City Ground, despite numerous managerial changes.
Robinson joins Jack Rodwell as the new arrivals so far in the January transfer window.