Santner has captained 24 T20Is and four ODIs and his first series in the full-time role will be against Sri Lanka starting in late December.
The first major event during his tenure will be the Champions Trophy in February before focusing on preparations for the 2026 T20 World Cup.
“It’s obviously a great honor and privilege to be asked,” Santner said. “When you were a kid, the dream was always to play for New Zealand, but to have the opportunity to officially lead my country in two formats is special.
“It’s a new challenge and I’m excited to get stuck into the important period of white-ball cricket ahead of us.”
Head coach Gary Stead explained that they were conscious not to increase Tom Latham’s workload as Test captain. Santner is also the first option in both white-ball formats.
“In Tom Latham we have an accomplished and experienced captain who has led the team admirably in all three formats,” Stead said. “Tom is doing a great job as full-time Test captain since taking up the role in October and we look forward to allowing him to concentrate on that job which requires a considerable amount of time and energy.”
“Mitch is a fantastic team man and leads by example in all facets of the game. He has an incredibly calm and collected personality and has great respect in the dressing room, which will serve him well.
“He has a lot of experience leading the T20 team and did a good job when he captained the ODI team last month, so he already has a good understanding of what it means to lead the team. I’m sure Mitch will also bring his own ideas and style. of leadership to the position.”
Santner has recently enjoyed a resurgence of his Test career with Man of the Match performances against India in Pune and England in Hamilton, but New Zealand now have a light schedule in the format through 2025.