Piers took aim at the traumatised 23-year-old after she flew back to the US the day after the atrocity, suggesting she should have stayed in the UK and visited the survivors.
But following Sunday’s One Love Manchester concert, Piers took to Twitter to apologise, saying he had “misjudged” the star.
He tweeted: “I thought Ariana Grande was wrong to fly off after #Manchesterattacks. But tonight she’s putting on a fabulous show.”
He then added: “I misjudged you, @ArianaGrande & I apologise. You’re an admirable young woman & this is a magnificent night. Respect.”
Piers was also full of admiration for Ariana’s performance at the concert at Manchester’s Old Trafford.
“I’ll say this too about @Ariana Grande, she has a cracking voice. By far the best vocal performance tonight…” he tweeted.
But in typical Piers Morgan style, he later added that he only apologises if he’s wrong, which “very rarely happens”.
Some of the biggest names in the music industry came together to honour the victims of the Manchester terror attack.
Ariana was also joined on stage by the Parrs Wood High School Choir, when the occasion became too much for one member.
Twelve-year-old soloist Natasha Seth ended up in tears as she performed ‘My Everything’ with her hero, melting the hearts of the nation in the process.
All net ticket proceeds will go towards the We Love Manchester Emergency Fund set up by Manchester City Council in partnership with the British Red Cross.
To donate £5 to the We Love Manchester fund, text LOVE to 70507. Texts cost £5 plus your standard network rate, with 100% of your donation going to the We Love Manchester fund.