The practice of deep frying a Mars Bar in batter, producing a deep-fried Mars Bar, is one reported in various media from the mid 1990s. Largely confined to chip shops in the west of Scotland (although it is said that it was invented in a chip shop in Stonehaven, on Scotland's North-East coast) and Australia, the "dish" was never a mainstream item, and its popularity with the media is in part an ironic commentary on urban Scotland's notoriously unhealthy diet.

In a study* published in The Lancet David Morrison (Greater Glasgow NHS Board, UK) and Mark Petticrew (MRC Social & Public Health Sciences Unit) surveyed around 300 Scottish fish and chip shops: 22% sold deep-fried Mars Bars; three-quarters of the shops had only been selling them for the past 3 years. Average sales were 23 bars per week, although 10 outlets sold between 50 and 200 bars a week. The average price per bar was 60 pence, and perhaps unsurprisingly, the younger generation were the main purchasers--three-quarters were sold to children and 15% to adolescents.

A deep-fried Mars Bar consists of an ordinary Mars Bar dipped in the batter usually used for preparing fish. This is then fried in the same deep fat fryer as the chip shop's usual fare (including fish, chips, black and white pudding, sausage, and often haggis). If the Mars Bar gets too hot it will melt, contaminating the frying fat. For this reason the Mars Bar is typically chilled before use, though a cold Mars Bar can fracture when heated.

Many (perhaps the majority of) Scottish chip shops still fry in beef dripping; this lends the exterior of the battered bar something of a beefy flavour.

With the decline of the fad, and the waning of media attention on it, actual frying of Mars Bars has become less common. It can however still be found in some fish and chip shops around the country, and in England and Northern Ireland. At least three chip shops in Dublin City, the capital of the Republic of Ireland, also offers the DFMB to their customers. A number of chip shops catering to tourists (particularly the legions of backpackers who visit Edinburgh's Royal Mile) still proudly declare they sell deep-fried Mars Bars, along with other treats such as deep-fried pizzas and haggis pakoras.

The deep-fried Mars Bar has also given rise to the frying of other confections, for example, Reiver's Fish Bar in Duns annually advertises an 'Easter Special' of deep-fried Creme Egg, although this is available all year.

It is known that the deep-fried Mars Bar was preceded by the deep-fried pizza. It was common practice in Angus to deep fry frozen pizza from as early as 1980.

Deep-fried Mars Bars are also available in Sydney, Australia at a few local beaches predominantly at the famous Bondi Beach. Also, many fish and chip shops throughout Australia, if not offering this directly, will for a small fee fry any chocolate bar brought into the shop. In New Zealand, deep fried Moro bars are available, along with a variety of other deep fried chocolates.

In addition, in some places in other European countries such as Spain, deep-fried Mars Bars are sometimes served as a dessert for British tourists.