Last year, the Napier Girls' High student was able to perform the song accompanied by the New Zealand Symphony Orchestra as part of the Young People's Showcase.
She also sang at Dannevirke's memorial service for Queen Elizabeth II last month.
The song she performed for Take the Mic, Home, was written late last year.
"It's written for someone who's really close to me, and I kind of wanted to portray that I see them as home, instead of like a physical place being home."
Molly first heard about the competition through the head of music at Napier Girls' High, who showed the class the poster promoting it, and she decided she would give it a shot.
She was notified she was in the top 30, but almost missed the email telling her she had made it through to the next round.
"It was really quite funny," her mum Steph said. "She spent 24 hours thinking she hadn't made the cut."
As part of the talent show, she had to film a video performing her song, which included storyboarding and production.
"That was so difficult," the 16-year-old said. "I was like looking at it for a solid week before I even started it."
As part of the show, Molly had to get votes from the public to be in the top three out of the 12 teenagers showcased.