For the first time in more than a quarter-century, there is no prominent candidate running to be elected governor. A dozen candidates are in the contest, but none has the charisma, wealth or name identification among voters compared with politicians in recent elections.

San Jose Mayor Matt Mahan announced Thursday that he is running for governor of California, jumping into an already crowded race less than six months before the June primary.

In an interview Wednesday evening, he touted a drop in San Jose’s homeless population that has outstripped state averages, as well as public safety gains and economic development, and said he hoped to...