Two elderly men have fended off a male and female intruder, one of whom was wielding a meat cleaver, during a brazen late night robbery at a Sydney boarding house.

Police say a 65-year-old man was in his bedroom when a man and woman entered the boarding house in Redfern on Friday night.

The pair allegedly demanded money and punched the resident in the face, before attempting to break into another room.

But as the male intruder kicked in the door of the second bedroom, two residents armed with sticks emerged and fought back, chasing the man from the house.

The female intruder, who allegedly punched a 52-year-old man in the face when he interrupted her as she was ransacking another bedroom, was arrested by police while attempting to flee.

The 21-year-old was charged with four offences, including armed robbery and will appear before Parramatta Bail Court on Saturday.

Police are searching for her accomplice.