Upset Australian Idol viewers have slammed the reality TV show after the surprising victory of Marshall Hamburger on Monday night.

The 19-year-old from the Sunshine Coast narrowly beat out fellow finalists Gisella Colletti and Iilysh Terallick – and many fans were not happy with the result.

‘GASP…. GISELLA…. GIRL… YOU WERE ROBBED!!! ROBBED!!!’ one shocked viewer posted to social media.

‘Australian Idol is a joke! How the hell did Gisella not make it through?’ a second person vented.

‘I don’t normally pay attention to Australian Idol but it’s honestly f***ed that Gisella was 10000x better than Marshall and Iilysh combined and yet… is Australia deaf???’ another sniped.

‘Australian Idol is less a singing competition, more a voting competition. Damn!!!’ an angry viewer chipped in.

Upset Australian Idol viewers have slammed the reality TV show after the surprising victory of Marshall Hamburger (centre)on Monday night. Pictured with Gisella Colletti (right) and Iilysh Terallick (left)

Marshall was lost for words by the life-changing victory.

The young performer walks away with a $100,000 cash prize and a recording contract with Sony Music Australia, following the record public vote.

Fighting back emotion, Marshall thanked his fans.

‘Thank you, Australia, thank you so much,’ he said.

‘You’re gonna see a lot of me in the future.’

Talking about his involvement on the singing competition, the excited teenager said, ‘I honestly can’t believe it. I’ve changed so much, I’ve definitely stepped out of my shell.’

As the contest progressed, it was Gisella who was eliminated first – leaving Marshall and Iilyish to battle it out.

Gisella bravely faced her disappointment and thanked her co-stars after the show.

The 19-year-old from the Sunshine Coast narrowly beat out fellow finalist Gisella Colletti

Many fans were not happy with the result and immediately posted their frustration

‘I left my heart out on that stage. I’m never turning back, no matter what happens. I’m so ready to go out there and make my own music,’ she said.

For their final songs Marshall picked the 1981 hit Every Little Thing She Does Is Magiic by The Police.

Iilyish, meanwhile, picked the Alanis Morrisette tune You Oughta Know.

Both selections were used when the up and coming stars auditioned for the singing competition.

Judge Kyle Sandilands gushed over Marshall’s talent.

‘I would love to get a psychic medium to find out which dead music legend you’ve reincarnated,’ the shock jock said.

‘It’s just not possible that such a young, fresh boy is such a seasoned genius musician.’

Marcia Hines also enthused over the Idol winner’s ability, while fellow judge Amy Shark added, ‘From the first second you came into that audition room and sat at that piano, you morphed into a superstar.’

Australian Idol producers have announced Marshall’s first album, The Idol Collection, which includes 11 songs from his best performances on the show.

During Monday’s nail-biting grand finale, it all came down to Gisella Colletti from Perth, Marshall from the Sunshine Coast and Iilysh Terallick from NSW