Cut each chicken breast half into 4 pieces.
Combine the chicken, broth, tomatoes, onion, lemon zest, lemon juice, herbes de Provence, salt and pepper in a 6-quart slow cooker.
Cook on High for 1 hour, 30 minutes or on Low for 3 hours, 30 minutes.
Stir in orzo and olives; cover and cook until the orzo is tender, about 30 minutes more.
Let cool slightly.
Sprinkle with parsley before serving.
