The concert is to air in 38 countries.
His visit comes after Queen Elizabeth met with victims of the attack.
The star-studded benefit concert will take place on Sunday.
ET is on the scene as the concert shapes up. Ariana Grande, the Black Eyed Peas and more will perform.
Katy Perry, Justin Bieber, Coldplay and others will also be performing at the benefit concert on Sunday.
Ticketmaster is working to make sure no resellers take advantage of the event.
Katy Perry, Justin Bieber, Miley Cryus and a Manchester school choir will also perform during the show, which will air live on the BBC.
The star-studded show will benefit the victims and families of those affected by the horrific bomb attack at her May 22 concert.
John Legend also paid tribute to a 15-year-old fan killed in the attack.
Joan Grande shared a powerful message with those affected by the bombing at her daughter's concert last week.
The 34-year-old reality star took to social media to share his condolences and offer words of strength for the families of the 22 victims killed and 59 left injured.
The actor and singer has penned emotional tweets about the tragedy that struck following his sister's Manchester concert.
22 people were killed after a suicide bomber attacked an Ariana Grande concert.
The 23-year-old singer penned an emotional letter on Friday revealing she would return to Manchester, England for a benefit concert in the victims honor.
