Prime Minister Anthony Albanese announced the 59-year-old business and community leader as the 28th governor-general after King Charles accepted the recommendation.
"Sam Mostyn is an exceptional leader who represents the best of modern Australia," Albanese said at Parliament House on Wednesday.
She will be sworn in as governor-general in July, taking over from current Governor-General David Hurley.
"I'm deeply honoured by this great privilege and look forward to representing the values, hopes and aspirations of all Australians," Mostyn said.
"I will never underestimate or take for granted the expectations that come with high office, and I am ready to serve with integrity, compassion, and respect."
Mostyn was appointed an officer of the Order of Australia in 2021 for distinguished service to business, the community and women.
With AAP.