Set the Instant Pot to Sauté mode. Add the ground beef and cook until browned, breaking it up as it cooks.
Add the diced onion and green bell pepper to the pot. Cook for 3–4 minutes, stirring occasionally, until softened.
Stir in the minced garlic, chili powder, ground cumin, salt, and pepper. Cook for 30 seconds, just until fragrant.
Turn off Sauté mode. Add the diced tomatoes, tomato sauce, and drained kidney beans. Stir well, scraping up any browned bits from the bottom of the pot.
Secure the lid and set the Instant Pot to Pressure Cook (Manual) on High for 15 minutes.
Once cooking is complete, allow a 10-minute natural release, then carefully quick release any remaining pressure.
Open the lid, stir the chili, and adjust seasoning if needed. Serve hot with your favorite toppings.