Thomas Riceman, 34, of the 3900 block of Chestnut Street, is also charged with attempted murder, aggravated assault and related offenses.
The stabbing happened just after 4 p.m. Sunday in the 1800 block of Walnut Street.
According to investigators, Riceman went inside a booth in the park and laid down.
That's when the city park ranger reportedly told the suspect he wasn't allowed in the booth.
Police say the suspect then stabbed the city employee in the face and head with a pair of scissors.
Sources say the park ranger is Hispanic. It matters in this case because police say Riceman yelled at the victim, "Go back to your own country."
Despite his injuries, the ranger was able to handcuff Riceman and wait for police to arrive.
The victim was transported to a nearby hospital and was last reported to be in stable condition.
The location of the crime surprised some people we spoke to.
"People come here on their break - I come here on my break - walk they dogs, have picnics," said Olivia Parker of West Philadelphia as she walked through the square on her way to work.
Peter Kourahanis of Point Breeze says he's been around Rittenhouse Square for a long time. He has his own thoughts about the incident.
"I don't believe this was a targeted incident. I believe it was an unfortunate mental illness thing, and it's the city," he said.
Dutch Wharton of West Philadelphia is a security guard himself.
"I work different times of day. This time it's cool. Later at night it's kinda sketchy, but that's part of being in Philly," he said.
People who live and walk through Rittenhouse Square say while they generally feel safe, they also stay alert.
"There's a lot of homeless people who are obviously mentally ill so I think that's the biggest fear," said Alanoff.
"I think, unfortunately, there's things happening here that I'm very aware of, but I think the city is doing much better now than before," said Avi Cohen of Huntingdon Valley.
People hope the place where they feel safe stays that way.
"(As a city) we've had our ups and downs, left and rights and everything in between," said Kourahanis, "but the city for the most part is safe."
Riceman is being held on $1 million bail.
RELATED: Check the 6abc Neighborhood Safety Tracker