Spray slow cooker with nonstick spray.

Mix cream cheese, sour cream, and mayonnaise in a large bowl until smooth.

Stir in artichokes, mozzarella, Parmesan, garlic, salt, and pepper evenly.

Spread evenly in cooker.

Cover; cook on low 2 hours, stirring halfway, until hot and bubbly.

Switch to warm; serve with crackers, baguette slices, or vegetables.