Heat the olive oil in a large pot over medium heat. Add the sausage and cook until browned, breaking it into small pieces with a spoon.
Add the sliced fennel and chopped onion to the pot. Cook for 5 minutes until the vegetables begin to soften.
Stir in the minced garlic and sliced carrots. Cook for 2 minutes until the garlic is fragrant.
Pour in the diced tomatoes and chicken broth. Add the dried oregano, salt, and black pepper. Bring the mixture to a simmer.
Reduce the heat to low, cover the pot, and cook for 25 minutes until the carrots and fennel are tender.
Remove from heat and stir in the chopped parsley before serving.