Poems and excerpts from his plays were read at the 15-minute ceremony, which followed his death Christmas Eve after a long struggle with cancer.
Some 50 people, including luminaries from Britain's literary world, gathered under a tree at Kensal Green Cemetery for the service.
"I might even show you my photograph album," Gambon read. "You might even see a face in it that might remind you of your own, of what you once were. You might see faces of others in shadows or cheeks of others turning or jaws or backs of necks or eyes, dark under hats, which might remind you of others whom you thought long dead but from whom you will still receive a sidelong glance if you can face the good ghost."
Gambon had read the same lines onstage Dec. 26 in the first performance of one of Pinter's plays since his death.
Poems were also read, including some dealing with Pinter's passion for cricket.
There are plans for a memorial event honoring Pinter, with details expected to be announced shortly.
Pinter, the son of a Jewish tailor, was raised in London's East End. As a young man he started writing poetry and acting, and later started writing plays, becoming one of Britain's leading dramatists.