Chris Wilder has made a third signing of the summer with the capture of central defender James Wilson.
Welsh international Wilson, 27, was out of contract and signs a two-year deal with the Blades.
"James is an athletic, mobile centre half and knows this division," said Wilder. "He turned down a contract at Oldham and had other options but we've had him with us for a few days, had a good look at him and he will be a good addition to our squad."
Wilson began his career with Bristol City and has also represented Brentford and Cheltenham Town before signing for Oldham Athletic in 2014 and he chalked up 100 league appearances before his contract expired in the summer.
Wilson follows defender Chris Hussey and Mark Duffy as the new faces at Bramall Lane.