Put water, sugar, and cherries in a medium saucepan and bring to a boil.
Once boiling, lower heat and let mixture simmer for about 15 minutes until cherries are bursting and mixture has thickened.
Strain syrup into a bowl, pressing down on the cherries with a wooden spoon or spatula to extract as much juice as possible.
Keep syrup in bowl or pour into a mason jar and place in fridge to cool completely before using. Syrup will continue to thicken as it cools.