The blast blew off the lower leg of Connor Golden, 18, during the July Fourth weekend. He now uses a prosthetic leg.
"I cannot find words that adequately express my gratitude for how much hope and support you all have given me," Golden wrote on a fundraising page
started for him.
"It is a beautiful thing to see how many people are by my side when a tragedy like this strikes."
He returned to school at the University of Miami last week, while also learning how to walk again.
"You'll see that I'm smiling in the photo [with the prosthetic leg]. That's not just because I'm happy to begin walking again. It's also because I am so grateful for the huge amount of love," he wrote.
Golden was injured when he and two friends jumped off a rock in the park on July 3, which set off the explosion. The other two were not injured, and they aren't considered suspects.
Authorities think the device was an "experiment with fireworks or homemade explosives," New York Police Department Deputy Chief John O'Connell said.
There was no fuse found in the explosive and no additional contents, such as ball bearings, to suggest an attack, officials said.
Investigators traced part of the device to a defunct bakery in New Jersey, but officials haven't identified anyone who could be responsible.