Emotions ran high as fans - many with colorful face make-up, costume bunny ears and the popular Manchester Bee t-shirts - poured into the city's Old Trafford cricket ground for the show headlined by pop star Ariana Grande, whose May 22 concert ended with 22 dead and over 100 wounded when a bomber struck.
"So moved by #OneLoveManchester", Fifth Harmony said.
Here are the most powerful speeches from the show.
Ariana added that she met Olivia's mom, and that the "One Love Manchester" show changed because of what her mom said.
The 23-year-old was wearing a One Love Manchester jumper and sang her songs Be Alright and Breakfree half way through the concert. We choose to love our families, our friends, and our country.
"Thank you to all those who helped in any way that night in Manchester".
In a statement released on Sunday, Grande and Bieber's manager Scooter Braun said the tribute concert will be to "honour those lost" in both the Manchester and London's atrocities.
"You've sang so much for us tonight". Look at what we're doing today and how important that is!
But there was also a jovial atmosphere, as police officers and security guards danced with music fans.
The English rocker opened the show, organized by Ariana Grande and her team to raise money for victims of the fatal terrorist attack following her Manchester show on May 22. The Manchester concert comes the day after attackers targeted the heart of London, killing seven people.
Grande collaborated with several of her friends, including Miley Cyrus, at her Manchester benefit concert.
Singer Ariana Grande has returned to the stage two weeks after a suicide bombing killed 22 people at her concert in Manchester.
The concert was broadcast live on BBC1.
"Our grandparents went through world wars so that we could live in freedom and now it's starting again". The show is broadcasting across the globe and proceeds will go to an emergency fund set up by the city of Manchester and the British Red Cross. "Music is meant to heal us, to bring us together, to make us happy".
Grande, who described herself as "broken" following the May 22 bombing, had immediately returned to the U.S., interrupting her Dangerous Woman world tour and later promising to return for the charity concert.
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