[Photo provided to China Daily]

She is also working on a crossover album with Sony Music, which is likely to be released later in the year.

Walker wasn't formally trained in singing while young but she was surrounded by music, thanks to her grandmother, a longtime music teacher at a local school.

As a child, Walker once had a crowd gathered around her as she sang a Beatles number while sitting near a stuffed toy in a shop, she says.

"I have been singing ever since I can remember. I don't feel nervous before performing. I just feel excited even when I am about to reach a high note that I have never done before," says Walker, who is also a member of the One Voice Children's Choir.

"I have always loved singing. It is one of the best ways to express how I'm feeling."

She decided to become a professional singer after she performed the US national anthem at a soccer game in Utah in 2013, and it fetched her much public attention.

"It wasn't until later that my mother told me that many people watched my performance. I'm really glad that people liked it," says Walker.

Things have changed a lot for her with popularity. Now, she has coaches and family members working alongside her on her schedules.

Her parents appear humble about their daughter's success. Her mother, Lisa Walker, tours with the daughter as her manager. Lexi is the fifth of the Walkers' six children.

"We just keep things open for her, taking her to nice places and to meet nice people. We let her decide what she wants to do," Lisa Walker says.

"I'm her manager but I'm a mother first."