But the 14-year-old was choking back tears as he accepted the prize – the loss of one person he wanted to celebrate with more than most still tearing at his heart.
His brother Banjo, 10, was tragically killed in a skateboarding accident near his Central Coast, NSW, home just weeks before the show started.
“There are so many different emotions running through my mind and my body,” Fletcher said in an interview on the show.
“I am happy and emotional, I just can’t believe it I am speechless.”
‘I’d just like to firstly thank my brother Banjo and my sister Gabby, my parents, family and friends and everyone who voted at home, the judges and the contestants,’ he said. ‘It’s been such a great time being on the show.’
Fletcher sealed up the win with another emotional rendition of Infinite Child, the song he wrote for Banjo, and first played to a standing ovation at his audition.
Sophie Monk was overwhelmed by his final performance and was brought to tears as Fletcher paid tribute to Banjo.
After the teen received a standing ovation from the crowd, the 36-year-old judge went on to gush about his performance as she wiped away her tears.
“I’m so sorry I’m crying in front of you,” an emotional Sophie said, adding: “I know Australia actually knows talent, I know they do and they’ll see it.”
Judge and former record label boss Ian ‘Dicko’ Dickson was also lavish in his praise.
“I guess what I didn’t realise at that moment until tonight was what a good song it is, such a great song. You’re a great songwriter mate.”
Others are noticing too, it seems.
Nicki Minaj shared Fletcher’s story with her 42 million Facebook fans in February, and Cody Simpson has reportedly hand-picked Fletcher to peform as a support act for his upcoming Australian tour.