Gather all ingredients.
Stir gelatin and hot water together in a small bowl until gelatin dissolves; pour into a saucepan.
Stir in coffee and sugar; bring to a boil over high heat.
Pour coffee mixture into a shallow, 9-inch square baking dish.
Chill in the refrigerator until solidified, 6 to 7 hours.
Cut coffee jelly into cubes to serve.
