In a medium saucepan over medium heat, cook sugar and water, stirring, until sugar has dissolved, about 3 minutes. Add blueberries and lemon zest and bring to a boil. Reduce heat to medium-low and bring to a simmer. Cook, stirring frequently, until blueberries have burst, about 5 minutes.
Let cool 10 minutes, then strain mixture through a fine-mesh sieve into a clean jar. Let cool completely.
Pour about 1 Tbsp. blueberry syrup into 8 champagne flutes. Add ¼ cup lemonade to each. Top off with Champagne. Garnish with blueberries.