Britney, 31, posted a couple of photos on her Instagram account which showed her sons, who both have September birthdays, dressed head to toe in their new fox motocross gear.
"Best way to celebrate a birthday!!!" wrote Britney next to a picture of her sons with their brightly coloured birthday cake. "My boys are looking good in their @foxracing gear…thanks Pete & Sallye!"
"My little future motor crosser and I ripping up the track... At 5 MPH!" said the Toxic singer with a photo of herself and Jayden on a bike. "Yee haw! Much love to @foxpetefox :)"
Sean, who turned eight on 14 September, and seven-year-old Jayden are Britney's children from her marriage to dancer Kevin Federline.
The Everytime singer is relatively private about her two children, although they occasionally step out with her in public.
In July Britney's boys were by her side as they attended the premiere of The Smurfs 2 which featured the track Ooh La La, a song Britney revealed she had recorded for her sons.
After Britney and Kevin's two-year marriage broke down the singer found love with her former manager Jason Trawick. The couple became engaged before going their separate ways in January.
The Louisiana-raised star is now in a relationship with David Lucado, who has been seen spending time and playing with his girlfriend's sons.
Sean and Jayden also have a new step-mother as their father Kevin recently tied the knot with his long-term girlfriend, Victoria Prince.