Saffie Roussos died aged eight of multiple injuries after suicide bomber Salman Abedi detonated a home-made device at Manchester Arena on May 22.
Her father Andrew Roussos told the BBC his family had "lost everything" when Saffie was killed.
He said: "We've lost everything. We have, we've lost everything, because life will just never be the same."
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He said he wanted to speak out so as not to let her birthday go by unmarked.
He said: "We didn't want to just let her birthday pass. Saffieloved the limelight and I just wanted to celebrate Saffie's birthday through doing this."
Saffie, who was at the concert with her mother Lisa Roussos and older sister, Ashlee Bromwich from Leyland, Lancashire, was a huge fan of Ariana Grande and was "elated" to be at the concert.
Ms Bromwich, who described being thrown to the ground by the explosion, said of Saffie: "She was Ariana Grande-obsessed, so to see how happy she was, it was just ... Obviously I had to go with her."
She added: "She was so happy, just elated all night."
Mr Roussos said: "You couldn't be out with Saffie without having fun, but her dream was to be famous. It was her everything and we bought her the tickets for Christmas.
"She was just counting the days, the seconds and it was just Ariana Grande until nine, 10 o'clock at night. And she would sing and dance every single song."
Mr Roussos, who said "all hell broke loose" at the arena after the bomb, was later told by a police detective that Saffie had died.
He described his wife, who is still recovering from her injuries, as "like a soldier" fighting her way back to health.
Although he had been "dreading" telling her Saffie was dead, he recalled that when she regained consciousness, his wife already knew.
He told the broadcaster: "She just looked at me and said 'She's gone, isn't she?' I said 'yeah'. She goes: 'I knew'."