Pickled walnuts are a traditional English pickle, made from walnuts. They are considered a suitable accompaniment for a dish of cold turkey or ham, as well as blue cheese. There is a reference to "a mutton chop and a pickled walnut" in The Pickwick Papers by Charles Dickens and a mention in Evelyn Waugh’s Brideshead Revisited.

Pickling is the process of preserving or extending the shelf life of food by either anaerobic fermentation in brine or immersion in vinegar. The pickling procedure typically affects the food's texture and flavor. The resulting food is called a pickle, or, if named, the name is prefaced with the word "pickled". Foods that are pickled include vegetables, fruits, mushrooms, meats, fish, dairy and eggs.