"Due to the tragic events in Manchester the Dangerous Woman tour with Ariana Grande has been suspended until we can further assess the situation and pay our proper respects to those lost," her management revealed in a statement.
"The London O2 shows this week have been cancelled as well as all shows through June 5 in Switzerland.
"We ask at this time that we all continue to support the city of Manchester and all those families affected by this cowardice and senseless act of violence.
"Our way of life has once again been threatened but we will overcome this together. Thank you."
Ari is set to perform six dates in Australia and New Zealand in September.
After today's devastating attack at Ariana Grande's Manchester show, the star has suspended her Dangerous Woman World Tour indefinitely.
Insiders close to the singer told TMZ that she has cancelled her London gig on Thursday and has put then rest of the European trip on hold.
Ari had upcoming dates in England, Belgium, Poland, Germany and Switzerland.
Ariana's manager, Scooter Braun, said, "We mourn the lives of children and loved ones taken by this cowardly act," adding, "We ask all of you to hold the victims, their families, and all those affected in your hearts and prayers."
TMZ have reported that the pop star and her management will re-assess the future proceedings when they're "emotionally ready".
Thoughts are with the victims and family members at this tragic time.