Combine salsa, peanut butter, coconut milk, lime juice, soy sauce, sugar, and ginger in the slow cooker; mix well.
Place chicken thighs in sauce; spoon sauce over chicken to coat.
Cover and cook on Low until chicken is very tender and sauce has thickened, 8 to 9 hours.
A meat thermometer inserted into the thickest part of a thigh should read at least 165 degrees F (74 degrees C).
Garnish with peanuts and cilantro before serving.
