Lance Cpl. Dylan Merola, of Rancho Cucamonga, was buried on Sunday at Forest Lawn Covina Hills.
Merola, who was killed in a bombing in Afghanistan last month, is the third and final Marine from Southern California to be laid to rest.
Former Marines and civilians thanked Merola, 20, and his family for his sacrifice.
John Pycior, a former Marine, said the loss of those Marines is “very difficult,” and “it shook a lot of us up.”
“Never forget them. We will always honor them, and … God bless their family,” Pycior said.
Correction: An earlier version of this article incorrectly identified the day of the funeral.