Whether food has gone rotten or been left open or it's just been too long since you've cleaned, the freezer can get stinky. Turning it off and deep cleaning is good to do annually but is not always practical. If you're having company or just don't have the time to deep clean, a few sprays and a box of baking soda is all you need.
Take everything out of the freezer and locate the food causing the smell. Figure out why it is stinky. If it needs to be covered or thrown away, do so.
Put frozen foods into the refrigerator. Items will stay frozen in the refrigerator for the short time you're cleaning the freezer.
Spray the freezer with an antibacterial kitchen cleaning spray, such as Lysol or Clorox brands. Take out shelves and spray them separately. Spray the crevices and back corners.
Use a clean, damp (not wet) rag or sponge to wipe down the freezer thoroughly. Repeat Step 3 and Step 4 to ensure not a spot was missed.
Open the top of a new box of baking soda about half an inch and place it into the freezer. There are "freezer box" baking sodas especially made for this purpose, but any baking soda will do. Place the box anywhere in the freezer that won't get in your way or spill. The baking soda will absorb bad smells.
Seal all frozen food items securely so that, if they do go bad, they won't smell up the entire freezer. Place the frozen items back into the freezer.
Replace the box of baking soda with a fresh box every 30 to 60 days to keep the freezer smell-free.
Using a cleaner with baking soda in it to clean will also help absorb odours.
Keep children and pets away from any cleaning or baking soda products.