He had the staunch support of General MacArthur. His opponent was Sergio Osmeña, who refused to campaign, saying that the Filipino people knew his reputation. However, in the April 23, 1946 election, Roxas won 54 percent of the vote, and the Liberal Party won a majority in the legislature. When the Philippines gained independence from the United States on July 4, 1946, he became the first president of the new republic. Manuel Roxas married Trinidad R. de Leon of Bulacan.
Hinuli ng mga bumalik na pwersang Amerikano si Roxas sa paghihinalang pakikipagtulungan sa mga Hapon. Pagkatapos ng digmaan, pinawalang-sala siya ni Heneral Douglas MacArthur at ibinalik ang kanyang nombramyento bilang opisyal ng Hukbong Sandatahan ng Estados Unidos. Ito ang nagbigay-buhay sa kanyang buhay politika, at sa suporta ni MacArthur, nanalo siya sa halalan sa pagkapangulo noong Abril 23, 1946 laban kay Sergio Osmeña.