A federal jury convicted Ahmad Khan Rahimi, a loner from New Jersey drawn to online calls to jihad and instruction manuals for carrying it out, of setting the explosives in the Chelsea neighborhood that blew out windows and sent shrapnel flying into buildings, cars and people during a two-day bombing campaign in and around New York City last year.

Mr. Ramini, 29, a stocky and bearded husband and father born in Afghanistan who lived most of his life in New Jersey, remained mostly expressionless in Federal District Court in Manhattan on Monday as he listened to a single word — “guilty” — called out over and over, eight times, by the jury foreman. He blinked rapidly and at times appeared to nod.

Terror attacks that kill and injure scores of people have become all too common around the world. The Chelsea explosion, which took no lives, was widely seen as a near miss. But its proximity to the site of the Sept. 11 attacks in Manhattan, and its callbacks to that day, sent shudders through the city 15 years later. The police have said there have been some two dozen terror plots against the city since then, the vast majority thwarted, but none that shook and smashed a block as strongly.

“Today’s verdict is a victory for New York City, a victory for America and its fight against terror, and a victory for all who believe in the cause of justice,” said Joon H. Kim, the acting United States attorney for the Southern District of New York, in remarks outside the courthouse.