Add sugar, orange zest, water, and orange juice to a medium saucepan. Stir to combine and then cook over medium heat until it comes to a boil.

Once boiling, add cranberries and cook, stirring often, until they pop and thicken, approximately 8-12 minutes. For a thinner sauce, cook less time. For a thicker sauce, cook the full time. Stir in the cinnamon after cooking.

Place in a bowl and let come to room temperature, then cover and chill until ready to use. It will thicken more as it cools.