You roast cubed sweet potatoes in the oven for about twenty five to thirty minutes at four hundred and twenty five degrees Fahrenheit until tender and lightly browned. Spreading the seasoned pieces in a single layer on a parchment lined baking sheet allows proper air circulation for crispy edges. Flipping the cubes halfway through the cooking time ensures even roasting on all sides. Whole sweet potatoes require roughly forty five to sixty minutes in the oven depending on their size.