The two sides agreed an undisclosed fee for Shackell and after he had talks in the Midlands, a deal was struck on Thursday afternoon.
Derby had already made previous bids for the defender this summer – which Burnley rejected – but Turf Moor boss Sean Dyche admitted the Rams had made the player an offer he couldn’t refuse.
Shackell previously spent the 2011/12 season at Derby and made 49 appearances before moving to Lancashire three years ago.
They have now been able to take him back to the iPro Stadium using some of the £250,000 Sky Bet Transfer Fund they won at Sky Studios in London earlier this month.
Shackell said: “I’m delighted to sign for Derby County and I’m really excited about the prospect of working with Paul Clement, his coaching staff and the rest of the players.
“There’s a really strong squad here and I’m happy to be part of it.
“Derby have been at the top end of the division for the last few years and I believe that we can be up there again this season, hopefully making that final step and reaching the Premier League.
“The club has made massive progress in recent times and after hearing the vision and ambition of Mel Morris, Sam Rush and Paul Clement, I couldn’t wait to sign.
“I know just how big a club Derby is following my previous spell here a few years ago and I’m well aware of the fantastic support that we have.”
Clement, appointed last month after leaving Real Madrid, added: “We’re thrilled Jason has become our latest acquisition. He is an experienced defender at both Premier League and Championship level.
“I know the Derby County fans will know all about his qualities already following his previous spell at the club.
“We feel that we have made a number of exciting signings this summer and this one certainly falls into that category. We’re delighted that he has chosen to join us and I look forward to working with him.”