Season the turkey thighs on all sides with salt, black pepper, and the Cajun seasoning.
Add the sliced celery, bell peppers, diced onion, and minced garlic to the bottom of the slow cooker.
Place the seasoned turkey thighs on top of the vegetables.
Pour the chicken broth around the thighs and drizzle the olive oil over the top.
Cover and cook on low for 6 to 7 hours until the turkey is tender and reaches an internal temperature of 165°F.
Sprinkle the chopped parsley over the thighs before serving.