The 24-year-old actor was joined by co-star Lily Collins and author Cassandra Clare.
“Getting hyped for mall appearance with @cassieclare and Collins. Who’s there? If anyone has a tie throw it at me. I kinda need one. X,” Jamie tweeted ahead of the event.
He added later on, “Philly. You guys are dope. Seriously. Mad love. Peace out. X.”
FYI: Lily is wearing a Maxime Simeons ensemble with Christian Louboutin boots.
20+ pics inside…