More than 11,000 rooms at 27 Riu hotels in Spain have started to be powered with 100% renewable energy.
The group will also see its Majorca head office tap into green energy.
A deal with Spanish energy provider Iberdrola aims to prevent 30,000 tonnes of CO2 emissions, the equivalent of planting approximately 300,000 trees.
The possibility of expanding the contract is being examined to include properties in other European countries and Mexico, where both companies also operate.
Riu chief procurement officer Bartolome Ensenat described the agreement is “a big step forward in our aim to make our operations sustainable”.
He added: “We are very proud to announce to our customers and colleagues that all the energy we use in Spain is 100% renewable, as certified by the Spanish National Markets and Competition Commission (CNMC).
“Iberdrola was the perfect partner to help us reach this goal and we hope that this is just the beginning, as we’ve set our sights high when it comes to sustainability.”
The company plans to invest 150 billion euros in renewable energy, electricity grids and energy storage by 2030.