Manager Bob Bradley says he intends to build his team around the Mexican international striker.
LAFC is still seven months from its major league soccer debut, but the franchise laid the cornerstone of its foundation on Friday when it introduced Vela.
"It's a big day for me," Vela said. "I'm the first player on this team. This is an honor. It's a lot of responsibility to be the first. I want to make a good history with you, and I hope we can enjoy a good time, win -- so thank you."
The 28-year-old has played the last six seasons in Spain and has been a mainstay on the Mexican National Team.
The club's ownership group includes comedian Will Ferrell. They will play at the brand new Banc of California Stadium being built at Exposition Park.