A walk-in freezer is a freezer used to store food in a frozen state for commercial use. Often referred to as simply a "walk-in" which may lead to confusion between the walk-in freezer and the walk-in cooler. With a temperature below 28 degrees F, the walk-in freezer is cooler than the walk-in cooler, which has a temperature between 28 and 40 degrees F. Whether a walk-in is a cooler or a freezer, it works the same way as the ones in a home: a reverse heat pump sucks the heat out of the enclosure. It is important to check that the heat produced by a walk-in can be properly ventilated.

These chilly enclosures may be freestanding structures outside or be built into a larger space and may be as small as 4 feet by 4 feet by 6 feet to as large as a warehouse. Having an outdoor unit is more expensive and its installation may subject to zoning restrictions although the noise will not disturb diners. In order to properly accomodate the needs of a business, there should be one cubic feet of storage for every 28 pounds of food.

The outside of the walk-in (or "skin") may be made of (listed in ascending order of price and durability) G 90 Galvanized Steel, Painted G 90 Galvanized steel, Aluminum, Galvalume or Stainless steel. G 90 Galvanized is most common. Shelving may be either wire racks or solid. Wire racks allow for greater air-flow but also increase the risk of food getting freezer burn.

Doors for a walk-in may have hinges on the right or left. Typically the hinges are heavy-duty. Some doors have a deadbolt lock or space for a padlock on the outside. On the inside they often have a release to prevent one from being trapped inside. If a walk-in does not have such an indoor release, it is a Good Idea to tell a coworker that you will be going into the walk-in. Cell phones typically don't work inside of a walk-in.

When removing anything from a walk-in, it is a Good Idea to use oven mitts, towels or a coat to protect yourself.

The average cost of a walk-in will range between $4,400.00 and $12,000. About 20% of a restaurant's energy consumption is in food storage. In order to reduce energy costs, a walk-in should be built in the coolest part of a building.

A walk-in freezer would also make a good place for a fight or to train for a fight—just like that one scene in Rocky where Sylvester Stallone punches cow carcasses hanging from the ceiling.