Preheat the oven to 300 degrees F (150 degrees C). Rinse pumpkin seeds in a colander. Spread out on paper towels and pat dry.
Coat a large baking sheet with cooking spray and spread the pumpkin seeds out in a single layer. Spray the tops of the seeds with additional cooking spray. Sprinkle the seafood seasoning evenly over the tops.
Bake for 30 minutes in the preheated oven, stirring occasionally, until dry and toasted. Cool for a few minutes before serving.