Starwood stockholders would receive 0.92 Marriott Class A share and $2 in cash for each share, Efe cited the companies as saying in a joint statement.
The combined company will be the world's largest hotelier, with 1.1 million rooms in more than 5,500 facilities across over 100 countries and an annual turnover of $2.7 billion.
The deal, subject to approval from both companies' shareholders and from regulators, is expected to close by mid-2016, the statement said.
Marriott CEO Arne Sorenson will head the combined company, whose headquarters is to remain in Bethesda, Maryland. Three Starwood directors will join an expanded 14-member board.