Durston spent seven years at Somerset
Derbyshire have boosted their batting line-up for the Twenty20 season by signing Wes Durston.
The 29-year-old scored a century in a recent game for the Unicorns, smashing 117 from just 68 balls.
Head of cricket John Morris said: "Wes put himself in the shop window with his magnificent innings against Sussex and we are delighted to have him."
But Durston, who spent eight seasons with Somerset from 2002 to 2009, will not feature in the County Championship.
He was selected to represent part-time club Unicorns, also known as ECB's Recreational XI, in the Clydesdale Bank 40 league having been released by Somerset at the end of last year's campaign.
Morris added: "Form and confidence are very important in cricket, particularly the short forms of the game, and Wes is brimming with both at the present time.
"He will add competition for places in our batting line-up and that can only be healthy as we strive for a successful campaign."
Derbyshire play their first home FP T20 match against Warwickshire on Wednesday, 9 June.