Danny Wilson has completed a triple signing following United's tour of Malta.
On returning to the UK, the boss concluded the finishing touches to all three deals over the weekend.
After recently securing the services of Chris Porter and Kevin McDonald on new contracts, Wilson has added free agents Tony McMahon and Matt Hill, in addition to Crewe Alexandra striker Shaun Miller, for an undisclosed fee.
Hill, who had a successful loan spell at Bramall Lane at the end of the last season, pens a two-year deal following his release from Blackpool.
Versatile defender Tony McMahon, formerly of Middlesbrough, has also agreed a two-year stay at the Lane.
Meanwhile, 24-year-old Miller arrives on a two-year contract, with the option of a third.
All three players could make their debuts against Rotherham United on Tuesday night at the New York Stadium. The game, which is all-ticket, is sold out for Blades supporters.
More reaction to the triple signing to follow on sufc.co.uk and BladesPlayer.tv