Gather all ingredients.
Zest lemons; place zest in a large glass bottle or jar.
Pour vodka into bottle with zest; cover loosely and let infuse at room temperature for 1 week.
After 1 week, combine water and sugar in a medium saucepan; bring to a boil but do not stir. Boil for 15 minutes. Remove from heat; cool syrup to room temperature.
Stir vodka mixture into syrup.
Strain into glass bottles; seal each bottle with a cork. Age at room temperature for 2 weeks.
Store bottled limoncello in the freezer until icy cold. Serve in chilled vodka glasses or shot glasses.
