The deal covers 10 of the new Boeing 787-8 series Dreamliners and 18 of the Boeing 737-800 series, Garuda said in a statement.
It said it will start taking delivery of the Boeing 787s in 2011-2013 and the Boeing 737s in 2006.
"Garuda Indonesia needs a modern fleet that can support the business expansion and service quality improvement" required by the airline, it said.
It said the Boeing 787 can cover a distance of 15,700 kms without stopping for fuel, allowing non-stop flights for routes like Jakarta-London or Jakarta-Vancouver.
Airlines have come under pressure from soaring world oil prices with Garuda hurt further by tighter international competition and the emergence of local low-cost carriers.
Garuda said the leasing agreement is a follow-up to a 1996 deal with Boeing for the operation of the Boeing 777-ER (Extended Range) series. Today's agreement was signed in New York, it said.
Garuda said it now operates a fleet of 57 aircraft, which includes six Airbus 330s.