Gather all your ingredients to make the process smoother.
Preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper.
In a large mixing bowl, combine peanut butter, brown sugar, and granulated sugar until smooth. Add eggs one at a time, mixing well after each. Stir in vanilla extract.
In a separate bowl, whisk together baking soda and salt. Gradually add to the wet mixture, stirring until fully incorporated.
Fold in rolled oats, chocolate chips, and M&M's until evenly distributed.
Drop rounded balls of dough onto prepared baking sheets, leaving 2 inches of space between each.
Bake for 10-12 minutes until edges are lightly golden. Allow to cool on baking sheets for 5 minutes before transferring to a wire rack.