Preheat the oven to 325 degrees F (165 degrees C). Place ham, cut-side down, on a roasting pan.
Cut skin off pineapple; remove any remaining brown eyes. Slice pineapple into ½-inch-thick rings; remove cores with a round cutter. Attach pineapple rings to ham with toothpicks.
Bake ham in the preheated oven for 30 minutes.
Whisk pineapple juice and brown sugar together in a microwave-safe bowl on MEDIUM, or small saucepan over medium heat until boiling and slightly thickened, about 5 minutes; glaze will be sticky and hot.
Pour 1/2 of the glaze evenly over ham and pineapple rings; bake 30 minutes more. Pour remaining glaze over ham.
Continue baking until a meat thermometer inserted into the thickest part of ham reads 140 degrees F (60 degrees C), 30 to 60 minutes more.
Let ham rest for 15 to 20 minutes before slicing.
