She told the Press Association: "We felt we had to unite with London - obviously we have lost our daughter and we felt we needed to come and unite with them and let them know Manchester is supporting them and we are all here for them".
Those who were at Grande's May 22 concert when the suicide bombing took place were offered free tickets; the remainder went on sale for $52.
Singer-actress Miley Cyrus' performance was all about her friendship with Grande, who noted the "Bang Bang" hitmaker's strength as a role model. "The only thing we'll feel here tonight is love, and positivity".
The show was broadcast across the globe and proceeds from the concert will go to an emergency fund set up by the city of Manchester and the British Red Cross. "I was paying homage and showing love to London and Manchester...#UKlove #whereIStheLOVE truly?" Backed by two singers and a guitarist, she delivered the song wearing all white, singing, "Throw your sticks and your stones, throw your bombs and your blows, but you're not gonna break my soul".
Grande made appearances throughout the show. "And unified. I think the kind of love you're displaying is the kind of medicine the world needs now".
Grande closed the show by inviting all the other performers on stage to help her sing her 2014 hit "One Last Time", before she closed with a moving solo version of "Somewhere Over the Rainbow".
"I'll be returning to the incredibly courageous city of Manchester to spend time with my fans and to have a benefit concert in honor of and to raise money for the victims and their families", she added.
A further terrorist attack in London on Saturday night had led to speculation that Ariana may pull the plug on the concert, but the singer opted to stand strong in the face of the attackers.
Braun said a TV broadcasting the concert was set up at Royal Manchester Children's Hospital, where some victims were still recovering.
The show opened with a minute of silence for those killed and injured in the attack.
Consolidated figures for One Love Manchester have not yet been revealed. "We need to try and find a way to overcome the fear".