Celebrating his 28th birthday in a big way, country crooner Brantley Gilbert popped the question to his lovely girlfriend Jana Kramer.

On Sunday (January 20), the birthday boy rented out the Ryman Auditorium Theater in Nashville where he got down on one knee in front of his "One Tree Hill" gal.

In a statement to PEOPLE, the couple said, "We could not be happier! We are so excited to share this special time with our loved ones and cannot wait to start the rest of our lives together."

The 29-year-old brunette beauty added, "I was so surprised! He asked my mom for permission before he proposed, which meant a lot to me."