Much of the applause went to Natasha Wong, from St Mary's School Cambridge, who won the competition in the end. "I was really shocked to be the winner because I totally did not expect it!" she said excitedly.
The competition was divided into two rounds. All 13 finalists performed their selected songs in the first round. But only the five with the highest scores qualified for the second round.
They all had a shot at being the winner of the "Most Popular Contestant" title awarded by the audience.
An a cappella performance by the group Momentum by the Show Choir kicked off the night. Several of the choir's members were Supernova 2011 finalists.
The MC for the night was Ming Jai, a YouTube star famous for his funny videos.
"This is quite a big competition for students, so we wanted to build this stage for people who love to and can sing," Betty Lau, a member of the organising committee, explained before the show.
All the 13 finalists generally earned positive comments from the judges. But, in the end, it had to go down to the top five.
The finalists who made it into the second round were Modee Leung from Wah Yan College Kowloon, Karton Ma from La Salle College, Groove from True Light Girls' College, and Yip Wing-ki from Chinese YMCA College, as well as Natasha.
In the second round, they all made an effort to display another side of their talents by performing different types of music.
Karton Ma of La Salle College
Karton, who won second prize, performed a playful Canto-pop song, which he admits "was not my usual style, but is one of my most-wanted-to-sing songs on my list".
Natasha enlivened her own funky song with a few monkeyish dance moves - in sharp contrast to her earlier performance of a soulful R&B number.
She even changed into a blinged-out jacket. But it was Natasha's addictively powerful voice that helped her win the Supernova 2012 contest.
"Joining Supernova 2012 most definitely changed me. Meeting new and different people, listening to different music styles - that made me want to try out new styles of music myself," she said.
The 15-year-old even has a YouTube channel showcasing her favourite songs.
Her first prize came with HK$8,000.
"I am going to use the prize money to get a new recording microphone for my YouTube channel and I'm going to give part of it to charity," she explained.
The girl band Groove was second runner-up. They won "the Most Popular Contestant" award.
The five-piece band from True Light Girls' College rearranged and performed Lady Gaga's The Edge of Glory.
The show also featured four guest performers: Endy Chow, Kary Ng, C All Star and Supper Moment.
Guest performer Endy Chow