Providing private cache allocation for power-collapsed processor cores in processor-based systems is provided. In one aspect, a processor-based system provides multiple processor cores, each residing within its own processor core power domain. Each processor core is provided with a private cache residing within its own private cache power domain, configured to be power-controlled independently of the corresponding processor core power domain. When a first processor core is placed in a power-collapsed state, a snoop controller corresponding to the private cache of the first processor core maintains power to the private cache power domain of the private cache, allowing the private cache to remain online. The snoop controller also enables allocation and snooping of the private cache by a second processor core while the first processor core remains in the power-collapsed state. In this manner, each private cache may be used for data-caching operations while its corresponding processor core is power-collapsed.