The policeman was identified as Sanjay Mahipati Patil.
Police spokesman inspector Gajanan Kabdule said that Patil, who was on duty at Kasheli bridge, spotted a woman jumping into the creek at around 3.30 pm today.
While his colleague Prabhakar Dudhale alerted the control room, Patil jumped into the water himself, and with the help of Nandu Patil, a local Shiv Sena leader, saved the woman.
The woman was taken to Thane civil hospital and the doctors said she was still unconscious but recovering. Police identified her as Sunita M Patil, around 35 years old.