Preheat the grill to medium-high heat.
Peel back the husks of the corn, leaving them attached at the base.
Remove the silk threads from the corn and carefully fold the husks back up.
Place the corn on the grill and cook for about 10-12 minutes, turning occasionally, until the kernels are tender and slightly charred.
While the corn is grilling, prepare the toppings. In a small bowl, combine mayonnaise and lime juice.
Once the corn is cooked, carefully peel back the husks, exposing the kernels.
Using a brush or spoon, generously coat each ear of corn with the mayonnaise mixture.
Sprinkle cotija cheese over the corn, followed by chili powder and chopped cilantro.
Serve immediately and enjoy the mouthwatering flavors of Mexican street corn.