Hearty Slow Cooker Vegetable Soup is the old-fashioned “fill you up” kind, rich in flavor and packed with nutrition! This easy vegetarian slow cooker recipe combines rustic vegetables with simple marinara sauce and vegetable broth to bring it all together. It makes a satisfying meal with a slice of crusty bread, or a tasty soup-and-sandwich combo!

overhead view of bowl of vegetable soup, surrounded by gold spoon, wooden cutting board with parsley, and black slow cooker in background

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What’s To Love About This Recipe

This hearty vegetarian soup has a simple and familiar flavor, making it easy to customize with different vegetables or added protein as desired.
This broth-based recipe is highly customizable so you can pick and choose your favorite veggies. The rich, flavorful broth, marinara, and simple mix of seasonings bring it all together beautifully!
Each vegetable in this recipe holds up well to slow cooking. Potatoes, carrots, and celery create a flavorful, rustic base, while zucchini adds a softer texture and blends into the soup.
In every serving packed full of nutritious veggies, you’re getting a healthy dose of fiber, vitamins and minerals, and added protein from beans and potatoes.
Rest assured that this is a true dump-and-go recipe! No sautéing required – just prep your veggies and keep it simple by adding everything straight into the slow cooker!
Vegetable soup is easy to make ahead and reheat or serve warm and fresh. Add a slice of bread with butter, or serve a cup paired with a sandwich. It’s a tasty, comforting classic!

Ingredients Needed

Yellow onion – Dice a yellow onion to add flavor to the soup base.
Carrots – Carrots add a classic, earthy element to the soup and get perfectly tender as they cook. Peel them for consistency, then slice into ¼-inch-thick rounds.
Celery – Celery, along with carrots and onions, creates the flavorful veggie stock essential to a hearty soup. Slice the celery the same thickness as the carrots, or about ¼ inch thick.
Yukon gold potatoes – Diced potatoes add to the homey, rustic quality of the soup. Leave the potato peel on for texture and to help them hold their shape.
Zucchini – Zucchini adds color and texture variety to every bite. Slice in half lengthwise, then into ¼ inch half moons.
Marinara sauce – A premade marinara sauce is the best hack to get amazing flavor with a condensed amount of ingredients. Choose a simple jarred sauce without added sugar to preserve the soup’s savory quality. This replaces tomatoes, tomato paste, and extra seasoning with a single ingredient and adds richness to the broth, keeping it from turning out thin and watery.
White beans or kidney beans – Canned white beans or kidney beans are a healthy source of protein and fiber. They add bulk to the soup and make it extra filling but not too heavy. Drain and rinse the beans before adding them to the slow cooker.
Vegetable broth – Add flavor to the base with plenty of vegetable broth.
Italian seasoning – This blend brings just the right balance of herbs to complement the marinara sauce.
Salt and black pepper – Finish off the seasoning with salt and black pepper, then adjust to taste.
Green beans (optional) – Add fresh or frozen green beans for extra texture variety and brightness. Stir in near the end of cooking to prevent them from becoming mushy.
Frozen peas (optional) – Frozen peas add a great balance of flavor with a touch of sweetness. Add these near the end as well to preserve texture.

vegetable soup ingredients to include bowls of diced onion, sliced carrots, sliced celery, diced yukon potatoes, sliced zucchini, marinara sauce, white kidney beans, green beans, peas, measuring glass of vegetable broth, wooden bowl of italian seasoning, and salt and pepper shakers

How To Make Slow Cooker Vegetable Soup

Add the onion, carrots, celery, potatoes, zucchini, marinara sauce, beans, vegetable broth, Italian seasoning, salt, and pepper to the slow cooker. Stir to combine.

overhead view of black slow cooker with all ingredients except for green beans and peas

Cover and cook on low for 6-7 hours or high for 3-4 hours, until the vegetables are tender.
If you choose to add peas or green beans, stir them in during the last 15-20 minutes of cooking.
Taste and adjust seasoning as needed, and serve warm.

overhead view of black slow cooker with cooked vegetable soup surrounded by wooden cutting board with carrots and celery, bowls and spoons, stalk of parsley, and wooden bowl of seasoning

Pro Tips

Make-ahead preparation tip: Prep the veggies, marinara, and seasonings (except potatoes) ahead of time, then combine them in a freezer-safe gallon bag for easy assembly at cooking time. Just chop the potatoes, add the broth, and add frozen green beans and peas as desired near the end.
This soup tastes even better after it sits since the flavors continue to deepen. This makes it a great choice for making ahead and storing in the fridge or freezer!
To keep the veggies from getting mushy, don’t overcook the soup beyond the designated cooking time, and don’t leave it on the warm setting for more than an hour. Additionally, the optional green beans and peas should be added near the end so they stay bright and don’t turn mushy.

Recipe Substitutions and Variations

To boost the protein content along with your veggies, try another variation with Slow Cooker Vegetable Beef Soup.
Fresh vegetables are preferred for the flavor and texture achieved through slow cooking. If you do choose to swap a frozen veggie for fresh (i.e., carrots or zucchini), add them within the last 20-30 minutes of cooking to prevent mushiness.
To customize with more vegetables, try diced bell peppers of any color, sliced mushrooms, or add frozen sweet corn kernels near the end.
Use either homemade or store-bought vegetable broth. Pay attention to sodium content or any additives in premade broth. Vegetable stock will also work, but you will need to increase the salt to adjust to taste.
If you don’t need a solely vegetarian recipe, this would be a great recipe to use leftover Homemade Bone Broth.
For a little heat in your veggie soup, add a pinch of smoked paprika or several flakes of crushed red pepper. For individual servings, you could also add a dollop of your favorite hot sauce.
Add some carbs and bulk to the meal with precooked pasta! While the slow cooker is finishing up, boil your favorite noodle variety on the stove and stir the cooked pasta into the soup just before serving.
For a creamy version, add a splash of heavy whipping cream to the slow cooker a few minutes before serving and stir well to integrate.

overhead view of black slow cooker with cooked vegetable soup with ladle inserted

How To Serve Slow Cooker Vegetable Soup

Serve up a hearty bowl of vegetable soup to make a filling meal with something toasty like sourdough or artisan bread on the side to dip in the flavorful broth. Keep it even easier with premade dinner rolls or breadsticks, or simple soup crackers for a crunchy finish. The broth base keeps it filling yet still light so you can serve it easily with any sides!

Serve a smaller cup of soup with a panini or fresh sandwich for a delicious lunch pairing. Grilled cheese, Homemade Turkey Lunchmeat Sandwiches, or a filling wrap would go perfectly!

overhead view of bowl of vegetable soup with gold spoon inserted sitting on a plate with a slice of bread, surrounded by another bowl of soup, wooden bowls of seasoning and salt, and orange tea towel

Storing and Reheating

How To Best Store Leftovers

The leftovers from this soup are absolutely delicious! It’s easy to refrigerate or freeze and continue to enjoy a freshly-flavored veggie soup in multiple servings.

Fridge

Let the soup cool completely before adding to an airtight container. Store in the fridge for 3-4 days.

Freezer

Let the soup cool to room temperature or in the fridge before freezing. Add to a freezer-safe bag or container, leaving some extra room for expansion. I personally love using Souper Cubes as an easy tool to portion leftovers into individual freezer servings..

Store in the freezer for up to 3 months.

How To Best Reheat Leftovers

Reheat leftovers from the fridge or frozen in a saucepan on the stove over medium heat, or heat in short bursts in the microwave, stirring in between.