GREATER MANCHESTER, England — The message onstage and in the crowd at “One Love Manchester,” a benefit concert for victims of the Manchester attack that was hosted by the pop star Ariana Grande, was one of defiance.

The event, at the Old Trafford Cricket Ground on Sunday evening, was Ms. Grande’s first appearance since a suicide bombing at her May 22 concert at the Manchester Arena killed 22 people, including children, and wounded dozens of others. It came less than 24 hours after another terrorist attack rocked the capital, London, about 200 miles away. Seven civilians died in the Saturday night attack, after a van screeched onto the sidewalk on London Bridge, slamming into pedestrians, before three assailants ran into a nearby open-air market area wielding large knives.

After the attack in London, Lily Garner, 22, said she felt some trepidation about coming to Sunday’s concert, but that she ultimately overcame it. “It puts you on edge a bit, but you can’t let those things affect you,” she said. “You can’t stop it from living your life, doing what you want to do.”