Combine the grape jelly and chili sauce in a slow cooker. Stir until well combined and the mixture is smooth.
Add the little smokies to the slow cooker, ensuring they are fully submerged in the jelly and chili sauce mixture.
If using, stir in the Worcestershire sauce for an added layer of savory flavor.
Cover the slow cooker and cook on low for 2-3 hours, or on high for 1-1.5 hours, stirring occasionally, until the sausages are heated through and the sauce is bubbly and slightly thickened.
Once heated through, reduce the slow cooker to the 'warm' setting to keep the smokies hot for serving.