Place the raw chicken breasts in a single layer at the bottom of a 6-quart slow cooker.
Add the rinsed quinoa, black beans, diced tomatoes (with juices), corn, onion, bell pepper, and garlic on top of the chicken.
In a small bowl, combine the chili powder, cumin, smoked paprika, salt, and pepper; sprinkle the spice blend evenly over the ingredients.
Pour the chicken broth over the mixture and stir the top layers gently to distribute spices.
Cover and cook on LOW for 6 hours or HIGH for 3 to 4 hours.
Remove the chicken breasts from the slow cooker and place them on a cutting board; shred the meat using two forks.
Return the shredded chicken to the slow cooker and stir well to incorporate with the quinoa and vegetables.
Adjust seasoning with additional salt or pepper if required, and serve hot.