The 27-year-old central defender, Rams manager Nigel Clough's sixth summer signing, has signed a three-year contract at Pride Park.
Clough said: "Jason brings leadership and experience qualities to Derby County and it's a tremendous signing for us.
"We've had to beat off stiff competition to land his signature and we believe he will have a big part to play in our coming season and our future.
"He's in the prime of his career and was Barnsley's standout player last season, as well as being one of the most impressive defenders in the Championship. Having watched him a lot last season it's clear he's a player who lives to defend."
Shackell, Barnsley's player of the season, came through Norwich's academy and made his debut for the Canaries as a 19-year-old. He moved to Wolves for £1million in August 2008, spent the 2009/10 season on loan at Doncaster and signed for Barnsley on a permanent basis last summer.