The patient who passed away was a South Coast resident in their 70s with underlying health conditions, officials said.
No additional information about the patient was provided.
The county also reported nine additional COVID-19 cases on Saturday, bringing the total to 469.
Five of the new cases were in the Lompoc Valley, including two at the Lompoc federal prison complex, which has been hard hit by the coronavirus.
Santa Maria had two cases, Santa Barbara had one, and the location of the last one was pending.
There were 107 people recovering at home, and 37 were being treated in local hospitals, including 13 in intensive care units.
To date, 305 people have fully recovered and 13 were pending an update.
Age groups for the new cases included one in the 0-17 group, one in the 18-29 group, two in the 30-49 group, three in the 50-69 groupo and two for whom the age was not disclosed.