The 43-year-old, formerly in the same role at the Magpies' Sky Bet League Two rivals Newport, replaces Julian Winter, who resigned this month after less than six months at the club, ahead of joining Huddersfield. However, he will not officially begin work at Meadow Lane until April 4.
Turner stepped down from his position at Newport in January. He has been involved in football for more than 20 years, starting at Bath before taking on the job of Cardiff's club secretary.
He joined Newport last summer having previously been at Plymouth, where he was general manager and secretary.
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"It's a privilege to be named as CEO of Notts County Football Club and I am absolutely delighted to be joining a club steeped in such tradition and history," Turner told the club's official website.
"Having worked in football for many years, I already know some of the people here, and when I was offered the opportunity to join it was a chance I just couldn't pass up.
"The number one priority has to be to get some stability and move the club back up the table and into League One as soon as possible. That's the shared vision of everyone here and, in my opinion, everybody has their part to play."
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