Heat the olive oil in a large Dutch oven or heavy-bottomed pot over medium heat until it shimmers.
Add the chopped onion, red bell pepper, and green bell pepper, cooking for 5 to 7 minutes while stirring occasionally until the vegetables are softened.
Stir in the minced garlic, chili powder, and ground cumin, cooking for 1 minute until fragrant.
Pour in the black beans, kidney beans, pinto beans, sweet corn, crushed tomatoes, and vegetable broth, then season with salt and black pepper, stirring to combine all ingredients thoroughly.
Bring the chili to a boil, then immediately reduce the heat to low, cover the pot with a lid, and let it simmer for 25 to 30 minutes, stirring occasionally, until the chili has thickened slightly.
Remove the pot from the heat and let the chili stand uncovered for 5 minutes to allow it to cool and thicken further before serving, garnished with fresh cilantro.