Angela Nash and Chris Gudgeon will add depth and further skills to the boards, says chair.
McKinnon has been acting CEO from earlier this year.
The appointments are aimed at driving its international expansion strategy.
David Chin has been appointed to lead the farmer-owned co-operative.
Anne Wilson has moved, with her family, to Christchurch to join the firm.
Dean Barker will replace company founder Iain Hosie.
Evan Bateup will join the firm from December 6.
Tony Giles was formerly the New Zealand Dairy Goat Co-operative chief executive.
Robert Fensham, Umesh Kumar, and Pieter Schoonrad will be led by Jason Molloy.
Kate Wareham joined the WSNZ board in late 2017.
