Sheffield United appoint Northampton Town boss
He replaces Nigel Adkins, 51, who was sacked on Thursday after the Blades missed out on the League One play-offs.
Wilder, 48, won the League Two title with Northampton this season.
"Sheffield United is a very big club for this division and Chris has always been a fan. I think this opportunity was too good for him to turn down," Cobblers chairman Kelvin Thomas said.
Ex-Blades defender Wilder will be joined at Bramall Lane by his assistant from Northampton Alan Knill and the club's head of sports science Matt Prestridge.
Wilder and Knill had discussions with relegated Championship side Charlton earlier this week before deciding against a move to The Valley.
Sheffield United finished in 11th place, eight points off the play-off places, and now face a sixth season in the third tier.
After his sacking Adkins tweeted: "I've met many good people in the 11 months I've lived in Sheffield. I wish you well. It saddens me to say goodbye."
The former Southampton and Reading boss was appointed in June last year on a three-year contract.
He succeeded Nigel Clough, who lost his job following defeat in the 2014-15 League One play-offs, but leaves the Blades after guiding them to their lowest league position since 1983.