A beverage container insulating sleeve for insulating a user's hand from a cold or hot beverage container while maintaining the serving temperature of the beverage. The material of the sleeve comprises insulating polyethylene foam. The sleeve is a low cost, lightweight, ergonomic, solution for consumers, advertisers, and anyone who sells hot or cold bottled beverages. The sleeve is further conformable to various beverage container styles and shapes due to a plurality of vertical slits formed therein.