Mr Bortolussi is expected to start in the role early next year and will succeed Geoffrey Babidge, who has been the chief executive officer on an interim basis since December 2019.
Mr Bortolussi has extensive international leadership experience in the consumer and retail sector and joins the company from his most recent role as group president for international innerwear at Hanes Brands.
He joined Pacific Brands in 2009 as chief financial and operating officer, taking over as chief executive officer in 2014.
In 2016, Hanes Brands acquired Pacific Brands and expanded Mr Bortolussi's role to cover Australasia and to develop new Asian markets, particularly with China.
Mr Bortolussi previously spent five years at Foster’s Group as chief strategy officer and held senior consulting roles at McKinsey and Company and PwC.
The a2 Milk Company chairman David Hearn said Mr Bortolussi secured the role following an extensive global search.
“David has demonstrated significant skill in guiding businesses through periods of significant growth whilst also effectively managing the changes that expansion frequently requires,” Mr Hearn said.
“The a2 Milk Company is going through a period of continued strong growth in dynamic markets and David’s skill set and comprehensive strategic and operational experience will serve the company well.”
Mr Bortolussi said he admired the a2 Milk Company's achievements.
“The team at a2 has created a very distinctive consumer proposition, amazing brand and strong culture with so much potential,” he said.
“I’m thrilled to have the opportunity to lead such a talented and experienced team, and to be part of the next phase of growth.”