The United Arab Emirates-based developer has acquired the stakes in the 149MW Rocksprings project in Texas and the 29.9MW Sterling project in New Mexico.
Both sites were completed in 2017 using GE 2.3MW and 1.72MW turbines.
Following the transaction, which is due to close in the first half of 2019, Masdar will own the sites with its partner, French developer Akuo Energy.
It is the Middle Eastern firm’s first energy project investment in the US.
"Expanding our presence in the United States is a turning point for Masdar's own energy activities and a step forward in our efforts to increase the portfolio renewable energies globally, which now includes more than 25 countries," said Mohamed Jameel Al Ramahi, CEO of Masdar.
"The United States offers excellent long-term development potential.
"Our goal is to increase our investments in the United States in the next few years, while continuing to strengthen our existing partnerships and explore new development opportunities," Al Ramahi added.
Masdar and Akuo previously partnered on the 72MW Krnovo project in Montenegro, the country’s first commercial wind site.
"The investment of Masdar will release capital that will be reinvested in new green-field projects in the US and internationally, where we continue our strategy to invest in renewable energies and other types of infrastructure," said John Laing CEO Olivier Brousse.