Obama, his family and friends attended private services Tuesday for Madelyn Payne Dunham at the First Unitarian Church in the Honolulu neighborhood of Nuuanu.
Dunham, known to friends as "Toot," died Nov. 2, two days before Obama won his election to become the nation's first African-American president. She was 86.
Obama did not speak to reporters at the small home that had been converted into a church. Aides said Obama's half-sister, Maya Soetoro-Ng, and her husband, Konrad Ng, also were present.
The family planned to scatter Dunham's ashes at a private ceremony later.
The Obamas are vacationing in Hawaii.