Rob Hewett will take over as chairman of Farmlands following the co-operative's annual meeting in November.
Incumbent chairman Lachie Johnstone confirmed last week he was not seeking re-election in this year's directors election.
Johnstone, of Waikato, joined the board of North Island-based Farmlands Trading Society Ltd in November 2000 and was at the helm when it merged with South Island-based CRT Co-operative in 2013.
The merger was one of the largest transactions in New Zealand that year.
He became the inaugural chairman of the newly created Farmlands Co-operative, which last year announced revenue of $2.39 billion and a profit of $12.2 million.