1 How long does ground beef last in the fridge once it is cooked? 2  Cooked ground beef will usually stay good for 3 to 4 days in the fridge and 3 months in the freezer. How long does raw ground beef last at room temperature? 2  Bacteria grow rapidly at temperatures between 40 °F and 140 °F; ground beef should be discarded if left for more than 2 hours at room temperature.