Natarajan joins Mainstream from Germany-based developer Juwi, where he filled a similar role. He will be based out of the company’s new office in Singapore.
Mainstream’s chief executive, Andy Kinsella, said the appointment was to support its "ambitious expansion plans" for the Asia-Pacific region.
Currently the company is developing an 800MW offshore wind project plus other onshore wind and solar sites in Vietnam. It also has a 120MW portfolio of potential wind sites in the Philippines.
"We… are evaluating a number of exciting opportunities across a range of new markets in the APAC region," Kinsella added.
To date, the firm has been more active in Latin America and Africa.
However, Mainstream said it had "the freedom to pursue large-scale development opportunities globally" after a "transformative year" in 2018 achieving a record profit of €487.5 million.