Joan Withers will extend her association with retailer Warehouse Group in September, taking over from Ted van Arkel as chair of the company.

Withers was a director on the Warehouse board from 1998 to 2005 and is a trustee of the Tindall Foundation which owns 21 per cent of the company.

New Warehouse chief executive Nick Grayston took over from Mark Powell in February, and Withers said his appointment had been a significant factor in her accepting the job.

"I have met Nick Grayston on a number of occasions and he is one of the key motivations for me taking on the role," Withers said.


"I think he's a great retailer and leader, and the experience he's had both in bricks and mortar retail but also on the digital side of retail and e-commerce means he has very unique experience in New Zealand," she said.

"He's operated around the world and I like his style and like him as a person.

"To me, the relationships I have as chair with CEOs is critically important so that was really the key motivation for me going in."

Withers took over as chairwoman of state-owned broadcaster TVNZ in March 2015, and agreed to extend her role until this April.

She said TVNZ had a good succession plan in place and it was a good time for her to step down.

She also planned to retire from the Treasury's advisory board in September, but will remain as chair of Mighty River Power and a director of Australia & New Zealand Banking Group.

She was named chairperson of the year in the 2015 Deloitte Top 200 Awards as well as winning the supreme award at last year's Women of Influence awards for her work championing diversity and gender equality.

"I've got a corporate governance career that goes back to 1997," she said.

"I've chaired Auckland Airport, TVNZ, [and] I'm chairing Mighty River Power so I hope to bring that whole repertoire of skills and experiences to the Warehouse role," Withers said.

"I've had a long association with the company [including as] a director between'98 and 2005.

"The Warehouse is a fundamentally important retailer in New Zealand and is very highly connected to New Zealanders."

Withers also spent two years as The Radio Network chief executive, four years as Fairfax Media chief executive and 15 years as an Auckland International Airport director and chairwoman.

She will take over from van Arkel on September 23, coinciding with the company's full-year result announcement.

Warehouse shares closed up 5c to $2.82 yesterday.