Combine vinegar, water, sugar, salt, and garlic in a pot over medium-high heat. Bring to a boil, stirring until sugar and salt dissolve. Remove pickling liquid from heat.
Stir jalapeno peppers into the pot. Let stand until slightly cooled, about 15 minutes.
Transfer jalapeno peppers to a large Mason jar; pour in pickling liquid to cover. Let cool to room temperature, about 30 minutes. Cover and refrigerate.
