Alvarez received the endorsement during the first round of voting.
"I think this continues to build momentum in the campaign," Alvarez said. "I'm thrilled with the support."
Mickey Kasparian, the president of the San Diego and Imperial Counties Labor Council, told 10News, "The issue was endorsing the candidate that would make a better San Diego that would stand for working families, that would stand for the middle class and David Alvarez is that candidate."
Other mayoral candidates – Mike Aguirre, Nathan Fletcher and Bruce Coons – were also at the San Diego Democratic Party Headquarters.
"I'll respect whatever decision they make," said Fletcher. "Partisan politics has never been my strong suit. I am really good at bringing people together to solve problems and that is what I think we need in our next mayor."
Alvarez is just 32 years old and a first-term councilman.
When asked if he had the experience to take on the challenge as mayor of San Diego, Alvarez said, "Absolutely, I have the experience and more than that, I have the enthusiasm."
A candidate must have 60 percent of the central committee vote to get an endorsement.