It is hard to believe that Lee Hi is already 18.

It seems like just yesterday the bubbly teen with a big voice was skatting around the stage on K-Pop Star.

Lee Hi's agency, YG Entertainment is celebrating their monster rookie's big birthday today with a series of congratulatory messages and pictures on their official blog and various social media outlets.

After winning second place on the reality singing competition, Lee Hi showed no signs of stepping out of the spotlight. She officially debuted as a soloist last year with the hit song "1.2.3.4" and topped the charts again earlier this year with her first album First Love.

To celebrate the jazzy young vocalist's birthday, take a look back at some of her biggest hit songs below.

Happy Birthday, Lee Hi!