It comes about a month after the Centers for Disease Control and Prevention made the same recommendation.
Cal/OSHA now states that an employee, regardless of vaccination status, can return to work after day five if they do not have symptoms and test negative.
If a worker cannot test or declines to test, they can return to work after 10 days.
Thursday, ahead of Cal/OSHA's decision, Fresno County started allowing some departments to adopt the same guidance.
"We recognize there are some staffing shortage potentials that are out there and so we wanted to give as much flexibility to department heads as possible," said Nathan Magsig, supervisor for Fresno County District 5.
It comes at a time when workforce shortages are spreading businesses and offices thin.
Fresno County is expected to expand Cal/OSHA's new guidance for isolation to all departments soon.
If you would like to see more on the CAL/OSHA recommendations, click here.