Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper for easy cleanup.
Cut the chicken breast into uniform 1-inch cubes and dice the red bell pepper into similar-sized pieces.
Drain and rinse the chickpeas, then use a clean kitchen towel to pat them very dry; this is the secret to getting them crispy in the oven.
In a large mixing bowl, combine the chicken, chickpeas, broccoli florets, and bell pepper.
Drizzle with the olive oil and sprinkle with garlic powder, sea salt, black pepper, and smoked paprika, tossing thoroughly to coat every piece.
Spread the mixture out onto the prepared baking sheet in a single layer, ensuring there is space between the ingredients so they roast rather than steam.
Roast for 20 to 22 minutes, tossing the ingredients halfway through, until the chicken is cooked through and the chickpeas are slightly crunchy.
Remove from the oven and immediately toss with the fresh lemon juice and lemon zest to brighten the flavors before serving.