Gather all ingredients. Preheat the oven to 375 degrees (190 degrees C).
Line cookie sheet(s) with parchment paper, silicone liners or aluminum foil sprayed with cooking/baking spray.
Beat butter, white sugar and brown sugar in a large bowl until smooth and creamy.
Beat in egg and vanilla until fluffy.
Stir together flour, baking soda, cinnamon and salt. Gradually beat into the butter mixture.
Stir in oats and raisins.
Drop 1.5 tbsp of batter 2 inches apart onto the prepared cookie sheet(s).
Bake in the preheated oven until golden brown, 8-10 minutes.
Remove from the oven and let sit on the cookie sheet(s) for 1-2 minutes before transferring to a wire rack to cool completely.