Preheat your Dutch oven over medium heat.
Add the olive oil to the Dutch oven and heat until shimmering.
Add the onion and cook until softened, about 5 minutes.
Add the garlic, carrots, and celery and cook until softened, about 5 minutes more.
Stir in the diced tomatoes, chicken broth, shredded chicken, cooked rice, and parsley.
Bring to a simmer and cook for 10 minutes, or until the soup has heated through.
Season with salt and pepper to taste.
Serve hot and enjoy!