Ravitch beat rival Victoria Shanahan 64 percent to 35 percent, with mail-in ballots and 366 of 366 precincts counted early Wednesday.
Ravitch did not return calls Tuesday night. Shanahan, who ran a low-budget campaign, said her share of the votes was evidence of dissatisfaction with her boss.
“I’m not shocked by it,” Shanahan said. “It definitely shows there are issues.”
The win came amid simmering controversy over whether Ravitch should file criminal charges against sheriff’s Deputy Erick Gelhaus in the shooting death of 13-year-old Andy Lopez.
Gelhaus shot Lopez seven times Oct. 22 after reportedly mistaking an airsoft BB gun the Santa Rosa teen was carrying for an assault rifle. The killing sparked numerous protests about police use of force and calls for criminal prosecution.
Ravitch, who has been reviewing a Santa Rosa police report on the shooting for the past four months, has declined to say what she will do or set a timeline for a decision.
It became a key campaign issue in an otherwise unremarkable race.
Shanahan criticized Ravitch for a lack of transparency and for not handing off the case to state prosecutors to avoid a conflict with Sheriff Steve Freitas, a political ally.
Last week, Shanahan appeared to be courting Latino voters, walking precincts in the Roseland neighborhood where Lopez lived.
But Ravitch, 55, a veteran campaigner with a significant fundraising advantage, prevailed.
She counted among her supporters the county Board of Supervisors, state and federal legislators and the Santa Rosa Police Managers Association.
Ravitch outspent Shanahan on the campaign trail by a margin of 2 to 1, according to early finance statements.