The pop star – who is “safe and well” following the massacre which left at least 22 dead – posted the emotional message on her Twitter account.
She said: “Broken from the bottom of my heart, I am so so sorry. I don’t have words.”
It was revealed this morning that she had cancelled her world tour following the horrific attack, which also left at least 59 injured.
She is believed to have axed her gigs in London later this week, and put her entire European tour on hold, according to TMZ.
London’s O2 Arena tweeted warning ticketholders that the concerts on Thursday and Friday may be cancelled in the wake of the attack.
The O2 posted a short statement confirming it would advise on whether the shows would go ahead shortly.
A representative from the singer’s label confirmed yesterday the 23-year-old is “okay”, although reportedly “in hysterics” following the bombing.
Footage appearing to show Ariana Grande’s tour bus arriving back at her Manchester hotel has since been shared on social media.
Tom Cross posted the video on Twitter, claiming the popstar’s bus had returned to the Lowry Hotel around “2 hours after reports of the first explosion”.
Ariana’s support act BIA tweeted: “GUYS WE ARE OKAY !!! THANK YOU WE LOVE YOU.
She added: “@tareemax was my angel tonight.”