Grease the inner pot of a 6-quart slow cooker with non-stick cooking spray.
Add rinsed quinoa, black beans, corn, diced tomatoes with juices, diced bell pepper, onion, garlic, and taco seasoning to the pot.
Pour the vegetable broth over the mixture and stir until all ingredients are combined.
Cover and cook on high for 3 to 4 hours (or low for 6 to 7 hours) until the liquid is fully absorbed and the quinoa is translucent and tender.
Turn off the heat and stir in 1.5 cups of the shredded cheese until incorporated.
Sprinkle the remaining 0.5 cups of cheese over the surface, cover, and let stand for 5 minutes until melted.
Garnish with fresh cilantro and serve immediately.