Combine cranberry, orange juice and sugar in a medium saucepan. Bring to a boil over medium-heat, stirring until sugar is dissolved.
Reduce heat and boil gently, uncovered, for about 10 minutes or until reduced by half. Remove from heat.
Cool to room temperature, stir in vodka and vanilla. Pour into a clean jar with a tight fitting lid. Store in frig.
Makes 3 cups.