Measure the area of brick work you'd like to add a textured effect to.
Select a fire-retardant textured paint product from your local hardware store or online. Make sure the product you choose is designed to be applied to a brick surface. You'll also need a primer as recommended by the manufacturer of your paint. A primer will help the top layer of textured paint bond to your brickwork and prevent chipping and cracking. A number of textured paints are available, including stucco-effect products and sand mixtures. Buy enough textured paint and primer to apply at least two coats of each to your fireplace's bricks.
Clean your brickwork thoroughly with warm water, detergent and a wire brush. Make sure you remove all dirt and debris by vacuuming the area once it's dried.
Protect the area around your brick fireplace with plastic sheeting and masking tape. Make sure any surrounding woodwork or painted surface is properly masked off before you begin applying any primer or paint.
Apply one coat of primer to your bricks using a paint brush. Allow this to dry and apply a second coat. If you're working with particularly porous bricks and the primer does not seem to be taking well, apply an additional coat.
Roll your textured paint onto your brickwork. Don't worry about applying it too evenly. An uneven finish will add to the texture of your finished fireplace. Once your first coat has dried, apply a second.
Add a glaze to your dried paintwork with a paint brush if recommended by the manufacturer of your paint.