Slow Cooker Tomato Sauce

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Who needs to stand over a bubbling pot all day, when you can make an amazing tomato sauce with practically no effort?! This slow cooker tomato sauce is easy, versatile, and full of flavour.

Slow cooker tomato sauce in a jar.

Hellooo, best tomato sauce I’ve ever made! I’ll admit, I often resort to using jars of shop-bought tomato sauce, just because I can’t always be bothered to stand there simmering a pot for ages – but this slow cooker tomato sauce is the answer to my prayers. It takes just 5 minutes of hands-on prep time, then you can just leave it to do its thing!

Slow cooker tomato sauce in a jar.

Rich tomato sauce

To make a rich tomato sauce, you usually have two options:

Either you cook your own sauce from scratch in a pan, and allow it to bubble away for a while to become nice and thick and tasty.

Or, you admit defeat, and open a jar.

Well, if you have a slow cooker, you now have a third option available to you: just throw some ingredients in the slow cooker, and leave it to bubble away without needing supervision. Hurrah!

I’ll admit, I don’t use my slow cooker as often as I probably should, but making tomato sauce from scratch is one of the best uses for it that I’ve ever found.

There’s no risk of the sauce bubbling over, or sticking to the bottom of the pan – you can walk away and forget about it for a few hours (although, I’ll admit this is pretty tricky when your house is slowly filling with the smell of Italy…)

Raw ingredients for slow cooker tomato sauce in the pot.

Simple, wholesome ingredients

The ingredients in this slow cooker tomato sauce are simple.

  • Chopped tomatoes
  • Diced red onion
  • Finely minced garlic (I used the stuff that comes pre-minced because I’m extra lazy!)
  • Tomato puree / paste
  • Herbs (both fresh and dried!)

In other words: all things that you would expect to find in a classic tomato sauce. No hidden ingredients, no preservatives or artificial flavours, just wholesome ingredients that wouldn’t look out of place in an Italian grandmother’s kitchen.

Chunky slow cooker tomato sauce in the pot.

Slow cooker tomato sauce

I let my sauce bubble away in the slow cooker for about 6 hours, but you can really just leave it for as long as you need to. More cooking time will give an even richer sauce, but it’ll still be delicious even after only 4 or 5 hours.

When the sauce is cooked, you can either leave it nice and chunky, or give it a quick blitz with a hand blender.

I did blend mine, but not all the way – I left it with a bit of texture.

If you don’t have a hand blender, just make sure you chop your onion quite small initially, and your slow cooker tomato sauce will still be delicious left chunky.

Blended slow cooker tomato sauce in the pot.

Slow cooking in the Instant Pot

If you have an Instant Pot at home, you might recognise the stainless steel pan from my photos. I do have a regular Crock-Pot as well, but since the Instant Pot has a slow cooking function, I thought I’d give it a try this time. One of these days I might get rid of my standalone slow cooker – anything to save a bit of counter space!

Of course, you can use any kind of slow cooker for this recipe, but here are a few directions for using the slow cooker function on your Instant Pot, if that’s the route you decide to take:

  1. Close the lid, and make sure the valve is set to ‘venting’.
  2. Press the ‘slow cook’ function button twice to change the pressure level to ‘more’, which is roughly equivalent to a regular slow cooker’s ‘high’ setting.
  3. Press the + button to set the timer for however long you like. It’s better to set it for longer than you need, as you can always stop it early – I went for 7 hours initially, but stopped it after just over 6.
  4. Then just let it cook! Unlike when pressure cooking, you can take the lid off whenever you like to check how it’s going (just don’t do it too often or you’ll let all the heat out!).
Instant Pot set to slow cook for 7 hours

How can I use this tomato sauce?

This slow cooker tomato sauce is so versatile. It would be impossible for me to list all the uses for this sauce, but here are just a few ideas:

Let me know in the comments if you have any other brilliant ideas!

Slow cooker tomato sauce in a jar

Can I freeze homemade tomato sauce?


This recipe makes a nice big batch of tomato sauce (about a litre / 4 cups), so don’t feel you need to use it all up in one go. It seems pointless to go to the effort of making sauce from scratch if you’re only going to use it for one meal, so I deliberately made a nice big batch!

If you don’t want to use all the sauce within a few days, you can freeze it – either in one big tub, or separated into smaller portions if that’s more useful. Just defrost a tub in the fridge overnight, or microwave on the defrost setting.

Slow cooker tomato sauce in a jar

How could I adapt this slow cooker tomato sauce?

As you know, I love adapting recipes! I can never make something the same way twice, even if I’m following one of my own recipes. It’s always fun to put a new spin on something to make it feel a bit different.

Here are a few ideas for how to transform this slow cooker tomato sauce into something new:

  • Add some curry spices to the pot, then stir through fresh coriander (cilantro) and a dash of cream just before serving to make a luxurious curry sauce. Perfect with paneer!
  • Give the sauce a Mexican vibe with some chilli powder and smoked paprika. You could even add a tin of black beans for some extra texture. Use to make amazing vegetarian enchiladas or cheesy quesadillas!!
  • Get some extra veg into your sauce by adding grated carrot or grated courgette (zucchini), which will melt right down into the sauce. Finely chopped spinach will cook right down too!

I’d love to hear how you plan to use your slow cooker tomato sauce – let me know in the comments or send me a photo of your creation!

Slow cooker tomato sauce in a jar

Slow cooker tomato sauce

Who needs to stand over a bubbling pot all day, when you can make an amazing tomato sauce with practically no effort?! This slow cooker tomato sauce is easy, versatile, and full of flavour.

If you’ve cooked this recipe, don’t forget to leave a star rating!

5 from 11 votes
Print Pin Comment
Prep Time: 5 minutes
Cook Time: 6 hours
Total Time: 6 hours 10 minutes
Servings: 4 cups
Calories: 72kcal
Author: Becca Heyes


  • 3 x 400g tins chopped tomatoes (~ 4 cups in total)
  • 1 onion, roughly chopped (I used a red onion)
  • 5 cloves garlic, minced (or 3 tsp lazy garlic)
  • 2 tbsp tomato puree (tomato paste)
  • 1 tsp dried thyme
  • Few sprigs fresh basil, chopped
  • Salt
  • Black pepper


  • Add all the ingredients to the slow cooker, and mix to combine. Cook on high for 5-7 hours (if you’re using the slow cook function of your Instant Pot, make sure the valve is set to ‘venting’, and slow cook with the pressure set to ‘more’).
  • You can either leave the sauce chunky, or blend it with a hand blender until it reaches your desired consistency. If you’d like a thicker sauce, continue to cook on high with the lid off for another hour or two.


Nutrition Facts
Slow cooker tomato sauce
Amount Per Serving (1 cup)
Calories 72 Calories from Fat 20
% Daily Value*
Fat 2.2g3%
Saturated Fat 0g0%
Cholesterol 0mg0%
Sodium 313mg13%
Potassium 108mg3%
Carbohydrates 11.8g4%
Fiber 2g8%
Sugar 6.5g7%
Protein 1.8g4%
Calcium 50mg5%
Iron 1.4mg8%
* Percent Daily Values are based on a 2000 calorie diet.

Nutritional information is approximate, and will depend on your exact ingredients. Please calculate your own nutritional values if you require accuracy for health reasons.

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My cheesy tofu meatballs are absolutely perfect served with this slow cooker tomato sauce!

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    1. Personally I’d just throw them in, roughly chopped up, but then I always like to go for the laziest option. If you’re planning to blend the sauce anyway, I don’t think the skins should make too much difference.