Stir salsa, taco seasoning, lime juice, and cilantro together in a slow cooker until well combined. Add chicken breasts and spoon salsa mixture over top to coat.
Cover and cook until chicken is no longer pink in the center and the juices run clear, on Low for 6 to 8 hours or High for 4 hours. An instant-read thermometer inserted into the center should read at least 165 degrees F (74 degrees C).
Shred chicken in the crock with two forks, then mix with the sauce.