Preheat oven to 400 degrees Fahrenheit (200 degrees Celsius).
In a large mixing bowl, combine the cubed chicken and diced sweet potatoes with olive oil, salt, pepper, garlic powder, oregano, and smoked paprika until thoroughly coated.
Spread the chicken and sweet potato mixture in a single layer onto a large parchment-lined baking sheet.
Roast for 25 to 30 minutes, or until the chicken reaches an internal temperature of 165 degrees Fahrenheit and the sweet potatoes are fork-tender.
Divide the cooked brown rice equally into four meal prep containers.
Layer 1/2 cup of fresh baby spinach into each container over the rice.
Distribute the roasted chicken and sweet potato mixture evenly among the containers.
Allow the bowls to cool slightly before sealing lids; refrigerate for up to 4 days.