Heat the olive oil in a large pot over medium heat. Add the onion, carrots, and celery, then cook for 5 minutes until the vegetables start to soften.
Stir in the garlic and cook for 1 minute until fragrant.
Add the lentils, diced tomatoes, vegetable broth, oregano, and basil. Bring the mixture to a boil, then reduce to a simmer and cook for 25 minutes until the lentils are tender.
Stir in the cannellini beans and kale. Cook for 5 more minutes until the kale wilts and the beans are heated through.
Season with salt and black pepper to taste before serving.