The name change was approved in the Los Angeles County Superior Court on Friday. The 31-year-old Lakers forward did not appear in court for the procedure.
Metta is the first name, which in the Buddhist tradition means loving kindness and friendliness toward others. His last name is World Peace.
"Changing my name was meant to inspire and bring youth together all around the world," World Peace said in a statement.
He first made the request back in June, but the change was delayed because of outstanding traffic warrants.
His publicist says the next step is legally changing the last name of his 8-year-old daughter Diamond. Eventually, she'll be known as Diamond World Peace.