In your slow cooker, arrange the chicken thighs in a single layer across the bottom. For 4 thighs, use a 4-quart slow cooker. Adjust the size as needed.
In a separate bowl, whisk together the soy sauce, ketchup, honey, garlic, and basil. Once combined, pour the mixture over the chicken thighs.
Place the cover on the slow cooker and cook the chicken on low for 6 hours or on high for 3-4 hours.
