"It was exactly one week ago, even to the hour, even to the minute," Trump said, reflecting on the July 13 shooting in Pennsylvania that left him with a bloodied ear, killed one supporter in the crowd and left two others injured.
"I stand before you only by the grace of almighty God," he added, the white gauze on his ear now replaced by a skin-coloured bandage.
"I shouldn't be here right now. Something very special happened."
Trump was joined by Ohio Senator JD Vance at the pair's first event together since they became the Republican Party's nominees at the Republican National Convention in Milwaukee.
"I find it hard to believe that a week ago, an assassin tried to take Donald Trump's life, and now we have got a hell of a crowd in Michigan to welcome him back on the campaign trail," Vance said, speaking before Trump's arrival.
During his speech Trump mocked the Democrats, comparing former House Speaker Nancy Pelosi to a "dog" and saying the party wanted to kick US President Joe Biden off the presidential ticket.
"They have a couple of problems. No.1, they have no idea who their candidate is," Trump said to laughter and jeers.
He questioned critics who called him a threat to democracy.
"I'm saying, 'What the hell did I do for democracy?' Last week, I took a bullet for democracy."
Downtown Grand Rapids saw a significant police presence, with officers stationed on nearly every block, while others patrolled on horseback and bicycles.
Attendees were required to pass through a metal detector upon entering the indoor arena, yet the presence of security inside appeared consistent with previous events.
