It happened Tuesday around 10 p.m. on a BX6 bus near Hunts Point Avenue and Lafayette Avenue.
A 35-year-old man was riding the bus when the three suspects came up from behind and grabbed his iPhone out of his hand, police said.
The three suspects got off the bus and when the victim went after them to try to get his phone back, one of the suspect pulled out a gun and shot the man in the leg, according to cops.
The suspects were seen on surveillance video.
Anyone with information should call police or Crime Stoppers at 800-577-TIPS or visit www.nypdcrimestoppers.com.