Dellums, who served more than 25 years in the U.S. House of Representatives, was elected to his first four-year term as mayor in 2006.
The 74-year-old Democrat said in a statement he was proud that he had increased diversity on the city's boards and commissions and engaged more residents in the political process.
"(As) I reach the end of this term, I am proud to see an Oakland that is more engaged, more enlightened and more empowered to continue the important work that lies ahead," he said in the statement.
Former Senate President Pro Tem Don Perata is among the candidates running for the post.
PHOTO CREDIT: Oakland Mayor Ron Dellums speaks during an event at the State Capitol, Friday Dec. 12, 2008. Brian Baer, Sacramento Bee.