In a large bowl, combine ground beef, breadcrumbs, egg, milk, ketchup, Worcestershire sauce, garlic powder, salt, and black pepper. Mix gently until just combined.
Shape the mixture into a loaf and place it on a trivet inside the Instant Pot.
Spread a thin layer of ketchup on top of the meatloaf.
Secure the Instant Pot lid, set to Manual/Pressure Cook on high for 25 minutes.
Once cooking is complete, allow the pressure to release naturally for 10 minutes, then quick release any remaining pressure.
Remove the meatloaf carefully and let it rest for 5 minutes before slicing and serving.
Notes
For extra flavor, serve with mashed potatoes and steamed vegetables.