Heat olive oil in a skillet over medium heat. Add diced onion, sliced carrots, and sliced celery. Cook for 3-4 minutes until vegetables begin to soften.
Transfer the sautéed vegetables to the crock pot.
Add the boneless skinless chicken breasts to the crock pot on top of the vegetables.
Pour in the chicken broth.
Add minced garlic, dried thyme, dried parsley, ground black pepper, salt, and bay leaf to the crock pot.
Cover and cook on low for 5 hours.
After 5 hours, remove the chicken breasts from the crock pot and shred them using two forks.
Add the rinsed rice to the crock pot and stir to combine.
Return the shredded chicken to the crock pot and stir.
Cover and cook on low for an additional 1 hour, or until the rice is tender.
Remove the bay leaf before serving.
Ladle soup into bowls and serve warm.