Hannah's only experience in front of a crowd so far was earlier this year at a school production, when she performed for about 100 parents.
"I feel really special about my job of switching on the lights.
"And I am also really excited about meeting Stan Walker," the little girl said.
Mother Karen entered Hannah after seeing the competition for children aged 6 to 12 - run by power company Vector - advertised online.
Ms Underwood said Hannah was "ecstatic" when she found out she had won.
"She was like, 'Oh my god', screaming and yelling.
"She's a very confident girl, she likes to do that kind of thing, so to do it on such a large scale is really exciting."
Hannah, who lives in Stanmore Bay on the Whangaparaoa Peninsula, is so confident she has even told her mother to keep clear of her while she's on stage.
"I said to her I would be right there if she wanted me, and she said, 'I don't want you on stage with me'," Ms Underwood said.
"She just wants to be out there on her own."
Where: Auckland Domain
When: 7.30 tonight
• Complete alcohol ban
• Grafton Bridge closed to vehicles
• Use public transport, as parking is limited
Reserve day: Tomorrow
• Performers include Stan Walker, X Factor winner Jackie Thomas and runner-up
• Benny Tipene, Vince Harder and Frankie Stevens
• Fireworks display to close the night
• Concert screens 7pm tomorrow on TV3
