Heat the olive oil in a large skillet over medium-high heat.
Add the ground beef to the skillet and cook until browned, breaking it into small crumbles with a spatula.
Stir in the diced onion, green bell pepper, and minced garlic, sautéing for about 4 minutes until the vegetables soften.
Transfer the beef and vegetable mixture into the slow cooker insert.
Add the kidney beans, diced tomatoes, tomato paste, chili powder, cumin, sea salt, black pepper, and water.
Stir all ingredients until well combined and the tomato paste is fully incorporated.
Cover and cook on low for 6 to 8 hours or on high for 3 to 4 hours to allow the smoky flavors to meld.
Ladle the hot chili into bowls and serve immediately.