The former chief executive of Grant Thornton Sweden will assume the role from January 2018 after 16 years working at the Swedish arm of the accountancy firm. He also spent five years as chairman of the board.
The current CEO is expected to leave at the end of 2017 after eight years leading the global firm.
Nusbaum said, “I am delighted that the board has chosen a strong, innovative leader in Peter who will inspire the people of Grant Thornton, our clients, and our communities throughout the world.
“I have worked closely with him over the years and I am confident that after a smooth transition he will continue the journey to execute our Growing Together 2020 strategy and continue to build an exciting future for this great organisation."
Scott Barnes, chair of the board of governors at Grant Thornton, said, “As a former chair of the board, Peter has deep knowledge of the global organisation and will inspire confidence in our CEOs.
“He has a reputation for coaching and developing people at every level and I believe his passion for people and leadership and his open, transparent style will resonate with the next generation at Grant Thornton.”
The appointment of the future CEO was approved the board, including CEOs of Grant Thornton member firms from 14 countries and two independent directors following a selection process carried out with external experts.
Grant Thornton International is based in London and operates across 130 countries.