Valens attended San Fernando High School and became a popular recording artist after being discovered in Pacoima.
He was known for quite a few hits, including "La Bamba" and "Come on, Let's Go."
Valens was portrayed on the big screen by Lou Diamond Phillips in the 1987 film "La Bamba."
Valens died at the age of 17 in a plane crash in 1959 that also took the lives of Buddy Holly and JP "The Big Bopper" Richardson.
Local leaders say it's important to recognize him on what would have been his 81st birthday.
"As a congressman, I get to do some pretty cool things, but naming this post office after Ritchie Valens really gives me goosebumps because this is home," said Rep. Tony Cárdenas.
"I'd like to thank all of you to keep my brother's memory alive," said Valens' brother Mario Morales. "We love you very much. God bless you all and let's keep on rocking."
Officials posted a plaque for him at a wall at the post office on Van Nuys Boulevard.
They also unveiled a mural that will be painted at the location next month.