Gather all ingredients.
Combine water, vinegar, sugar, kosher salt, garlic, and oregano in a saucepan over high heat. Bring mixture to a boil, stir in jalapeño peppers, and remove from heat.
Let mixture cool for 10 minutes.
Pack peppers into two 8-ounce jars using tongs and cover with vinegar brine mixture. Let pickles cool completely at room temperature.
Cover jars with tight-fitting lids and refrigerate until needed.
