Cooking Asparagus in the oven is a quick process. It takes just about eight minutes to cook at 400 degrees F. However, please note that every air fryer brand and model cooks differently. Depending on the size and design of your air fryer, it might take longer or less time to cook. If you use the same air fryer settings, you might have different results. If the same settings are applied, and the results are unexpected, please adjust the time to get your desired outcome.