Season the chicken breasts with salt, pepper, garlic powder, and onion powder.
Heat olive oil in a skillet over medium heat and sear the chicken breasts on both sides for about 3-4 minutes.
Place the seared chicken breasts in the crockpot.
Add diced onions and mixed vegetables over the chicken in the crockpot.
Sprinkle dried thyme evenly over the mixture, and add the rice on top.
Pour in the chicken broth over the top of the rice.
Set the crockpot to low and cook for 6-7 hours, or high for 3-4 hours.
Once done, shred the chicken directly in the pot using two forks, then stir everything together gently.
Taste and adjust seasoning with additional salt and pepper if necessary, then serve.