Turner has headed the media organisation for four-and-a-half years and guided the company through last year's receivership and debt restructuring.
She was a former head of Radio and in November 2009 replaced her close friend and former group CEO Brent Impey.
Sussan has a background in sales and has been a survivor in a company that was ravaged in the collapse of the leveraged buyout boom last decade.
MediaWorks - especially the radio arm - has maintained good operating profits though they have not been enough to cover the excessive debt that harks back to the price paid by private equity group Ironbridge.
Announcing Turner's resignation today, MediaWorks chair Rod McGeoch praised her performance.
"Sussan has successfully navigated the company through one of its most challenging times," he says.
"We've come out the other side with a restored balance sheet and a stellar trading performance across the Group this year." Turner has worked with MediaWorks for 30 year going back to the days when the company was controlled by the current economic development minister Steven Joyce - she was managing director of Radio Otago.
Before that she was in the hospitality sector. Turner's departure follows a relatively smooth path for the company since its banker owners put the firm into receivership and emerged last November as the new shareholders of the company.
McGeoch said the Board is actively seeking a replacement. However insiders believe that the board - including McGeoch and Julie Christie - will not be looking far.