Place the shredded cheddar cheese and softened cream cheese in a mixing bowl.
Using an electric mixer, beat the cheeses together for 2 to 3 minutes, or until well combined.
Add the mayonnaise to the cheese mixture.
Mix until the mixture is smooth and evenly blended.
Add the garlic powder, paprika, onion powder, and dried mustard.
Stir until the seasonings are fully incorporated.
Add the drained diced pimentos.
Gently mix until the pimentos are evenly distributed throughout the cheese mixture.
Cover the bowl or transfer the pimento cheese to an airtight container.
Refrigerate for at least 10 to 15 minutes before serving.
Stir before serving, if needed.
Serve chilled with crackers, vegetables, bread, sandwiches, or preferred accompaniments.