The Rams have re-signed the defender from Championship rivals Burnley on a three-year contract.
The centre-back has explained that Derby’s vision for the future convinced him to move to the iPro Stadium for a second spell.
“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,” the 31-year-old told Derby’s official website.
Shackell was a key player for Burnley for the past three seasons and was important for the Clarets during their Premier League campaign of 2014-15.
The former Barnsley defender played in all 38 league games, but he failed to prevent Burnley from getting relegated to the Championship.
The former Wolves man created nine chances, had a pass accuracy of 77% and a shot accuracy of 25%, and won 154 headers, two dribbles and 17 tackles.
Shackell is going to add experience and quality to the Derby defence and is going to enhance Paul Clement’s side’s chances of a top-two finish in the Championship in the upcoming 2015-16 campaign.