"This city took a hit, there's no doubt, but Boston, like a lot of other cities, is resilient," said Donovan, of nearby Wellesley.
Bombing victim Jeff Bauman, who lost his legs in one of the blasts and was led from the scene in a wheelchair, also attended and smiled on a massive television screen.
As the members of NKOTB took the stage to perform, member Joey McIntyre, who had finished running in the marathon 10 minutes before the bombs went off, choked up.
"I happened to be on a bench in Copley Plaza, Copley Square," McIntyre said, "but I don't care where you were that day, because this happened to all of us."
Surprise guests Boyz II Men joined NKOTB on stage for "One Sweet Day" in tribute to those who lost their lives in the attack.
Other acts taking part in the benefit show included country singer Jason Aldean and comedian Steven Wright. James Taylor performed "Sweet Baby James" with Carole King on piano.
More than once, the words "Boston Strong" were met with cheers and fist pumps from the energetic crowd.
"I love that phrase," enthused Boston comic Lenny Clarke, whose cathartic set featured a foul-mouthed, one-man reenactment of the capture of bombing suspect Dzhokhar Tsarnaev. "You know what I don't love? 'Shelter in place.'"
Boston area residents were locked down, told to shelter in place, a few days after the bombing while authorities searched for Tsarnaev, who was found hiding in a boat in a backyard in suburban Watertown. Tsarnaev's older brother, Tamerlan Tsarnaev, had died after a shootout with police.
The suspects, ethnic Chechens from Russia, are accused of setting off two pressure cooker bombs packed with shrapnel near the marathon's finish line, killing three people and injuring more than 260 others. Their mother has insisted they are innocent.