Gather all ingredients.
In a medium-sized saucepan, combine the sugar, water, vinegar, soy sauce, cornstarch, and ketchup.
Place the saucepan over medium heat and bring the mixture to a rolling boil, ensuring to stir constantly.
Continue stirring until the sauce thickens to a smooth, glossy consistency.
Once thickened, remove the saucepan from heat and let the sauce cool slightly before serving.
Enjoy!