The boy, a Marin City resident, was arrested around 2:30 p.m. Sunday as he was walking in the courtyard of the Golden Gate Village public housing development at 300 Drake Ave., Lt. Barry Heying said.
Heying said the teen is believed to be one of two suspects who stole a cellphone from a bus passenger around 9 p.m. on June 26.
The victim, who just had gotten off the No. 80 bus from San Francisco after a Giants baseball game when the robbery occurred, was beaten but no weapon was used, Heying said.
Other robberies and assaults at or near the bus stop since June 16 have involved handguns, Heying said.
Heying said the sheriff's office expects the teen's arrest will lead to more arrests.
"I've always felt we were dealing with more than one or two suspects -- probably a small band of suspects," Heying said.
The suspects in many of the robberies have been described as black males between 15 to 22 years old who wore black hooded sweatshirts and black or blue pants.