Warm a large skillet over medium heat. Crumble in the ground beef and season with salt and black pepper, stirring to break up the meat.
Add the diced green pepper, diced onion, and minced garlic to the skillet. Sauté about 4–5 minutes, until the vegetables soften and the beef is no longer noticeably pink. Drain off excess fat.
Transfer the beef-and-vegetable mixture into the slow cooker. Stir in chili powder, cumin, ground chipotle, cayenne, Worcestershire sauce, and liquid smoke until evenly combined.
Add the drained kidney beans, undrained diced tomatoes, and tomato sauce to the slow cooker. Mix well so the ingredients are distributed evenly.
Cover and cook on low for 8 to 10 hours or on high for 4 to 5 hours, until flavors meld and chili reaches your desired thickness.
Taste and adjust seasoning as needed before serving. Ladle into bowls and offer toppings such as diced red onion, corn chips, sliced jalapeños, shredded cheese, sour cream, and fresh cilantro.