Step 3: Slow Cook the Chicken - Cover the slow cooker and cook on High for about 2 to 3 hours, with roughly 3 hours being a good target for average sized chicken breasts. Cooking time can vary depending on the thickness of the chicken and the way
your slow cooker runs, so start checking on the earlier side if your chicken breasts are thin. The chicken is ready when the thickest portion reaches 165°F. I try not to leave chicken breast cooking much longer than necessary because that is how a tender dinner can turn dry.