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 from the heat.

Stir jalapeño peppers into the pot. Let stand until slightly cooled, about 15 minutes.

Transfer jalapeño peppers into a large sterilized Mason jar using tongs or a slotted spoon. Pour in pickling liquid to cover. Let cool to room temperature, about 30 minutes. Seal the jar and store pickles in the refrigerator.