Australian mining engineer Palmer was Newmont's COO and promoted to the dual roles of president and COO last year.
In February, former Rio Tinto executive Rob Atkinson was announced COO, effective June 1, freeing up Palmer to take on the CEO role when Gary Goldberg retired in the fourth quarter.
Newmont said Goldberg would serve as executive advisor to support Palmer and the executive leadership team, from October 1 to March 31.
Board chair Noreen Doyle thanked Goldberg for his "exceptional leadership" and the foundation he had built, positioning Newmont Goldcorp as the sector's standout leader in long-term value creation.
The company said Palmer had also played a central role leading the Newmont-Goldcorp merger earlier this year and establishing the joint venture with Barrick Gold in Nevada.
