That includes all faculty, staff and students going for in-person classes at Fresno State and all other CSU campuses.
The university said the vaccinations should be completed by September 30.
Students and employees could, however, seek medical and religious exemptions.
The announcement comes amid rising cases of the coronavirus Delta variant in the state. California's health officials said Monday the Delta variant accounts for 83% of all COVID cases statewide.
Chancellor Joseph Castro said in a statement that the new requirement was an effort to ensure the health and well-being of CSU's students and employees.
"We urge all members of the CSU community to get vaccinated as soon as possible, and announcing this requirement now allows members of the CSU community to receive multiple doses of a vaccine as we head into the beginning of the fall term," he said.
The university said many of its campuses were hosting events to administer the vaccine, and that anyone who wanted to get vaccinated for the coronavirus should contact their campus for availability.