Preheat oven to 180ºC (175 degrees C). Place broccoli in the bottom of a 9x13 inch baking dish. Top with the chicken.
In a small bowl, blend the cream of chicken soup, cream of mushroom soup, mayonnaise, and lemon juice. Pour the mixture over the chicken. Top with cheddar cheese.
Bake 35 to 40 minutes in the preheated oven, until bubbly and lightly browned.