"Let's have fun. Let's be safe. Let's never forget our friends in Boston," Nutter said. "We are Americans."
The logo for the sticker features a Liberty Bell, a Boston Celtics four-leaf clover and the Love Park sign. The sticker raises awareness to the One Fund Boston, which Massachusetts Gov. Deval Patrick and Boston Mayor Tom Menino helped form to benefit the people most affected by the April 15 bombings.
"I think it's a wonderful opportunity for the City of Brotherly Love to show support for a city that suffered such a tragedy," said Kate Mastalski, who was in Rittenhouse Square when Nutter made the announcement.
A team of designers from the King of Prussia-based Cadient Group designed the logo after the CEO, Stephen Wray, said he felt compelled to do something to support the victims of the Boston tragedy.
Wray, a runner himself, said he had friends, colleagues and clients who had participated in the Boston Marathon. He said he was "frustrated" and "sad" by the act of terror, saying he didn't understand how "something so pure" as the Boston Marathon could be halted by a "senseless act of violence."
"I'm just one of thousands of people who wanted to do something to help," Wray said after he addressed the crowd. "I'm just fortunate enough to have my colleagues and friends listen to my idea and make it a reality."
Independence Blue Cross, the official sponsor of the Blue Cross Broad Street Run, embraced the idea. It was during the IBC's annual National Walk at Lunch Day event Wednesday when Nutter made the noontime announcement.
The walk event, featuring thousands of people coming to the park throughout the day, featured loud music as attendees performed dances such as the Electric Slide.
Even Nutter, after his announcement, did a few gyrations to "Sweet Caroline," which in recent years has been used by the Boston Red Sox as an unofficial anthem.
Joselito Huertas, the IBC fitness manager who rallied Rittenhouse Square with upbeat dancing Wednesday, said the Boston sticker "is great."
"It shows one nation, unity," Huertas said. "The logo is great with the Liberty Bell and the Love Park sign. It's cool."
Anyone seeking to contribute can make donations at OneFundBoston.org.
Contact Sulaiman Abdur-Rahman at email@example.com, or follow on Twitter @sabdurr.