Philadelphia police are still investigating the circumstances around why the child was left there, and have not said what charges the woman will face, if any.
They say the child is safe with family members.
Video of the young girl in a stroller drinking out of a bottle was posted by No Gun Zone Philadelphia, an anti-violence organization.
Police say the 18-month-old girl was found around 7:30 a.m. Saturday.
"The baby's sitting on E and Clearfield, in a stroller, by herself, no socks on, soaking wet, scars on her face and hands," Dayday Allen with No Gun Zone said.
Police say the toddler, who appeared to have abrasions on her face, was left with a stranger who called police after the child's mother didn't return.
She was taken to the hospital for evaluation, but police still didn't know her identity.
Police released the child's image on Saturday evening, and with the public's help, they were able to identify the girl and her mother.
Neighbors say they are still stunned by the whole ordeal.
"I didn't see nobody with her," said neighbor Taj Allen. "I just saw her over there drinking a bottle, just looking around all sad. Heartbroken."