The "Toxic" singer and her brother Bryan teamed up to introduce their little sister to the stage at country music mecca in Nashville, Tennessee.
It became a big emotional get together after Britney called Jamie Lynn her "heart and soul" and burst into tears, reported People magazine.
Her sister was also teary as she took the stage and hugged the 34-year-old pop star.
It then became clear the magical family moment was as much a surprise to Jamie Lynn as to fans in the audience as she said, "I can't believe that my whole family kept this secret from me!"