Rub jerk seasoning generously over chicken thighs. In 3 1/2- to 4-quart slow cooker, mix bell pepper and onion. Place chicken over vegetables.
In small bowl, mix broth and ketchup. Pour broth mixture over chicken.
Cover; cook on Low heat setting 6 to 8 hours.
Remove chicken from slow cooker; place on cutting board. Shred chicken with 2 forks; return to slow cooker, and mix well.
To serve, with slotted spoon, spoon chicken mixture into buns.