The updated vaccination policy is for anyone who accesses a university facility or its programs.
Students, faculty and staff members will need to get and report their booster dose by February 28, 2022, or six months after receiving their original vaccine.
CSU Chancellor Joseph Castro said the new requirement is the system's response to the rise in COVID-19 cases in California and the spread of the new Omicron variant.
"Implementing the booster requirement now will help mitigate the potential spread of the variant on campuses as they repopulate in January after the winter break," Castro said in a news release.
Like CSU's original vaccination policy, students and employees can seek medical and religious exemptions.