The victim was walking on 29th Street near 40th Avenue on Oct. 10 at 9:45 p.m. and talking on her phone using an earpiece when the suspect passed her from the opposite direction.
Police said he then he came up from behind and pushed her against a fence, grabbed the iPhone out of her pocket and fled on 29th Street.
Cops say the suspect is 30-35 years old and 6 feet tall. He was wearing army fatigue pants, a multi-colored bubble jacket, wool hat and black shoes.
Four other women have also been targeted in a series of knifepoint iPhone robberies last month. It was not immediately clear if the latest robbery is connected to that pattern.
Anyone with information in regards is asked to call Crime Stoppers at 1-800-577-TIPS (8477). The public can also submit tips by logging onto the Crime Stoppers website at WWW.NYPDCRIMESTOPPERS.COM or by texting their tips to 274637 (CRIMES) then enter TIP577.
All calls are strictly confidential.