Its 2018 profit is up from a €5.5 million loss the previous year, and follows the sale of its 450MW Neart na Gaoithe wind farm in Scottish waters to EDF Energy.
Last year, it also repaid all its corporate debt (€73 million) and secured a €90 million trade facility with lenders DNB Bank and HSBC Bank, which can be extended to €200 million.
The developer added that it is on track to raise a further €700-800 million of project finance in 2019.
This financing gives Mainstream RP "the freedom to pursue large-scale development opportunities globally", the developer stated.
It opened new offices in Scotland, Colombia, Singapore and Australia last year.
The developer plans to expand its footprint in its core Asia Pacific, Latin American and African markets, and is actively pursuing offshore wind projects in the UK, India, Vietnam and the United States, it said.
"Mainstream is poised to become one of a new class of renewable energy majors as the transfer of capital from fossil fuel to sustainable energy accelerates," said Mainstream group CEO Andy Kinsella.
"We now have a robust balance sheet and are unrestricted in our ambitions to help growing economies develop through the delivery of renewable energy capacity."
Mainstream RP has more than 10.5GW of new wind and solar PV projects in development worldwide, plus 707MW under construction. It has commissioned 804MW to date.
In September 2018, Mainstream RP returned to its core equity ownership structure following an institutional buyback. It is now privately owned by founder Eddie O’ Connor, employees and "a small retail investor base", the company said.