Slow Cooker Caramelized Onions

This slow cooker caramelized onion recipe is perfect if you want to make some caramelized onions in bulk. It’s so easy to get prepared and cooking quickly.

Slow Cooker Caramelized Onions

The onions will cook to have a lovely deep brown color and have flavors that will leave you wanting caramelized onions on everything. This method of preparing caramelized onions is so incredibly simple. It’s a surprise more people don’t do it.

Making caramelized onions at home is a great way to save on money. Store-bought varieties will often set you back five or more dollars. However, the ingredients in this recipe should only set you back a few bucks.

Traditionally you make caramelized onion in the fry-pan as it’s quicker. However, the slow cooker does a pretty good job and is perfect for cooking in bulk. A single batch of this recipe will last me a good couple of weeks.

Uses for Caramelized Onions

There are so many uses for caramelized onions that it’s impossible to list them all. Below is just a few examples on what you can do with this tasty condiment,

I absolutely love including this condiment as a topping on pizza. It adds quite a bit of flavor to the pizzas without overloading them. I certainly recommend giving it a try.

A caramelized onion toasted cheese sandwich is as good as it sounds. Again, I highly recommend trying it if you haven’t had it before.

Caramelized Onions in the Slow Cooker

Using some of the onion, you can make a delicious homemade dip. For a bit of extra flavor, I love adding some bacon bits, as they really take the dip to the next level.

You can even use the caramelized onion as a replacement to onion in dishes such as slow-cooked soups, pies, and so much more.

There are plenty more uses for this delicious condiment. If you have any ideas that you would love to share, then please don’t hesitate to leave a comment.

How to Store Caramelized Onion

Below are the two ways that I usually use to store this delicious condiment.

You can store the caramelized onion in a glass jar for later. It will keep in the fridge for about a week, maybe longer.

Caramelized Onions in a bowl

You can also freeze the caramelized onion so you can use it later. I would freeze it in serving sizes, so you don’t have to defrost everything for only a tablespoon of onion. It should last for about three months in the freezer.

If a video is your preferred way of learning, then you can find one right below. You can also find the full written recipe on how to make caramelized onions in the slow cooker underneath the video.

Slow Cooker Caramelized Onions Recipe

5/5 (100%) 1 vote
Prep Time15 Minutes
Cook Time12 Hours
Total Time12 Hours & 15 Minutes


  • 1 kg (2.2 lb) onions, sliced
  • 30 g (1.1 oz) unsalted butter
  • 1 Tbsp balsamic vinegar
  • 2 Tbsp brown sugar


  1. In a slow cooker, add the onions and scatter the cubed butter over the top.
  2. Scatter the brown sugar and the balsamic vinegar over the top.
  3. Cook on low for 8 hours.
  4. Leave the lid slightly ajar and cook for a further 4 hours. The liquid should evaporate and become thick and jammy.
  5. Serve & Enjoy

Recipe Tips

  • Don’t stress too much on the thickness of the slices of onion. The long cooking time will ensure that all the onion will be cooked over the course of a few hours.
  • You can leave the balsamic vinegar and the brown sugar out of the recipe, but the caramelized onions will not be as flavorsome.
  • If the onions don’t appear to be cooking fast enough, then you can turn the heat up to high. This heat increase will dramatically reduce the cooking time of these onions.
  • This dish will produce a strong onion smell, so if you’re not a fan of onion, make sure you have the slow cooker cooking under a ventilation fan.
  • Freeze the caramelized onion in ice cube trays. This method is excellent if you only ever need a single serving and not an entire jar full.

Note: I use a 5.5L (6 Quart) slow cooker for all the recipes that I have on this website unless specified. If you have a smaller or larger slow cooker, then you might need to adjust the ingredients.

Nutrition Information

Serving Size: 134g (4.7 oz)
Servings Per Recipe: 8
Calories Per Serving: 70
Amount Per Serving
Total Fat: 2.2g
Saturated Fat: 1.3g
Trans Fat: 0g
Total Carbohydrate: 12g
Dietary Fiber: 2g
Sugars: 6g
Cholesterol: 4mg
Sodium: 7mg
Protein: 2g

The information above is an estimate generated by an online nutrition calculator.

More Condiment Recipes

There are plenty of other condiments that you can make in the slow cooker.

The apple butter is certainly another condiment that is well worth making. It’s especially useful if you need to feed a crowd.

A BBQ sauce is super easy to make in the slow cooker and tastes absolutely amazing. It’s perfect if you love making all your condiments at home.

I hope that this slow cooker caramelized onion recipe is an absolute hit with your friends and family. If you have any feedback regarding this recipe, then be sure to leave a comment below.


  1. Avatar for Gilda Anderson
    Gilda Anderson on

    What size tablespoon should we use? A tablespoon here in Australia is 20 ml, I believe US is 15 ml, UK 25 ml.
    Thank you.

    1. Avatar for Gus
      Gus on

      Hi Gilda,

      I made use of Australian sized Tablespoons. However, this recipe is pretty tolerant to slightly different measurements, so any variant should still work.

    2. Avatar for Penny
      Penny on

      A tablespoon in the USA is 3 teaspoons, if that helps!!

  2. Avatar for LC
    LC on

    Approx how much does this recipe yield?

    1. Avatar for LC
      LC on

      Oh and does it matter what kind of onion you use? eg. white, brown, red?

    2. Avatar for Gus
      Gus on

      It will make roughly 1kg (2.2 lb) of caramelized onion. I recommend using brown onions for the best flavor. Both red onion and white onion may result in a slightly sweeter final product.

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