Kaplan, who said in late April that she had formed a committee to explore the possibility of running for mayor, joins City Councilwoman Jean Quan and former state Senate President Pro Tem Don Perata in running for the city's top job.
Mayor Ron Dellums hasn't yet announced whether he will seek re-election. His office didn't return phone calls seeking comment today.
While making her announcement to about 30 supporters at an art gallery in downtown Oakland, Kaplan said, "I want to make more jobs available for Oakland residents and make this a city where people can work and play without fear."
She said she wants to streamline the process for getting city permits, and she wants make city government more "responsive, effective and efficient."
Noting that Oakland has budget difficulties and a high crime rate, Kaplan said, "I want to provide for fiscal sanity and public safety at the same time and make it possible for everyone in the community to thrive."
Kaplan said she wants to encourage companies that do business in Oakland to give priority to hiring Oakland residents, which she doesn't think would discourage companies from coming to the city.
"East Palo Alto implemented a strong local hire program, and it didn't impede new businesses," Kaplan said.
Kaplan, 39, was elected to the at-large city council seat in 2008 with 62 percent of the vote. She previously served on AC Transit's Board of Directors for six years.
According to a statement issued by her campaign, Kaplan is the first openly lesbian elected official in Oakland.
"Of all the cities in California, Oakland has the highest per capita number of artists, lesbians and churches, and that's a beautiful thing," Kaplan said.
The filing period for mayoral candidates begins July 12 and ends Aug. 6. If, however, Dellums decides not to run again, the filing period will be extended until Aug. 11.