The 30 year old all-rounder joins the County Champions and helps to provide balance to the professional squad with his left arm spin.
Ian has represented England in one Test Match and 34 One Day Internationals.
Blackwell has scored 21 First Class centuries with a top score of 247*. He also supports his batting with some valuable wickets with his slow left arm spin taking nearly 240 First Class wickets.
As Twenty20 cricket gains more momentum Ian’s big hitting ability will have added value.
Head Coach Geoff Cook said “With Durham looking to constantly improve our squad when it became clear Ian was available we grabbed the chance of signing him.”
“I think it’s important to sign players of Ian’s quality and experience to continue the progress of the squad in all forms of the game.”
Durham Chief Executive David Harker added “We were delighted to win the LV County Championship last season but it is important that we learn lessons and continue to add quality players, such as Ian, to the squad when they become available.”