Attribute-based proxy re-encryption (AB-PRE) is a crucial variant of proxy re-encryption. It allows a proxy with a re-encryption key to transform a delegator’s ciphertext associated with an access policy into another ciphertext associated with a new access policy, enabling delegatees with matching attributes to decrypt the transformed ciphertext. However, a key limitation of AB-PRE is that the delegator cannot control which ciphertexts are transformed. As a result, the proxy, once given the re-encryption key, indiscriminately transforms all ciphertexts, effectively switching their underlying policies—an issue known as the all-or-nothing problem. It limits the system’s flexibility and practicality in real-world use cases. In this paper, we address this by proposing a primitive of Conditional AB-PRE (CAB-PRE), which extends AB-PRE by incorporating conditional re-encryption. In CAB-PRE, the proxy can transform a ciphertext only if this ciphertext satisfies a specific condition set by the delegator in the re-encryption key. We formalize the adaptive security of CAB-PRE under the context of honest re-encryption attacks (HRA). We also give a concrete construction based on the learning with errors (LWE) assumption, which attains designated security in the standard model.