The former England under-21 international previously spent the 2013-14 season on loan at the Rams and now joins on a permanent basis
Derby County have completed the signing of Andre Wisdom from Liverpool in a deal reportedly worth £4.5million, with the defender penning a four-year contract.
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The Championship side confirmed last month they had struck a deal with the Reds and agreed personal terms with the player.
And Derby sealed a deal for Wisdom on Monday after he successfully completed a medical, the 24-year-old following Curtis Davies to become the club's second signing of the close-season.