Combine the peanut butter, powdered milk, and honey in a mixing bowl. Mix until well combined.
Add the oats and mix until everything is well combined and the oats are evenly distributed.
Roll the mixture into small balls about 1 inch in diameter. Place the peanut butter balls on a lined baking sheet and chill in the refrigerator for 30 minutes to firm up.
These peanut butter balls can be stored in an airtight container in the refrigerator for up to a week.