McMillan, who played 260 internationals between 1997 and 2007, will work alongside head coach Ben Sawyer starting with the upcoming tour of England later this month.
McMillan had previously served as New Zealand’s batting coach between 2014 and 2019, a period that saw the team reach consecutive ODI World Cup finals. He had also featured as a fielding coach for Punjab Kings in the IPL in 2018. McMillan’s most recent assignment was as a batting consultant for Canterbury last season.
“He’s a proven coach with an extensive international playing career,” Sawyer said. “The players are excited to start working with Craig; they’re looking forward to having him on board for the upcoming tour to England.”
McCullum said he was looking to “drive the team forward” ahead of a busy schedule that includes the women’s T20 World Cup in just four months.
“I’m rapt with the appointment and to be back involved in coaching international cricket again,” he said.
“It’ll be great to be part of the White Ferns family as we head into a busy nine-month schedule with some exciting challenges ahead. I’ve watched these talented players a lot from close quarters over the past few seasons and can’t wait to join the management team in driving the group forward.”
New Zealand are scheduled to tour England for three ODIs and five T20Is, between June 26 and July 17. They will then travel to Australia for a three-match T20I series in September, before the T20 World Cup in October.