|Headquarters||Letterkenny, County Donegal, Ireland|
|Parent||Zed Candy Ltd.|
The business began as a wholesale and retail outlet on the Port Road in the town. The McKinney family began to make their own sweets and on 15 August 1927. The first sweets were made on the open coke fire in a shed at the back of the shop. The land on which the factory now stands was purchased in November 1929, the first sod was cut in February 1930. Six people were employed at the time.
The company at the time was known as Mayfield Confectionery but the name was quickly changed as another company in Manchester traded by this name. The company name was changed to Oatfield. The land on which the factory is built was known as Oatfield. The May was dropped and Oat was substituted and hence the name “Oatfield”. The weekly production of confectionery was about 3 tons. Today the company produces approximately 65 tons a week.
Sugar was purchased in the 1930s from Tate & Lyle. Glucose came from Manchester. They were delivered by ship and rail via Derry to Letterkenny railway station. Later, glucose was shipped from the Netherlands to the Letterkenny Port. Today, only Irish sugar and Irish glucose are used. Butter has always been Irish Creamery Butter.
By 1960 Oatfield decided to stop marketing packed sweets made by Cadburys, Rowntree, Urney's Chocolates, Bassetts Licorice Allsorts, Jacobs Biscuits, William and Wood, Ritchies Mints and Milroy Confectionery. The company now began to focus on entirely selling Oatfield sweets. This was a major decision and proved a major success for the company.
Exporting began in August 1964. The first sweets were exported to Northern Ireland. The sweets are exported on a worldwide scale which includes countries as far away as the United States, Canada, Hong Kong, Australia, Kuwait, Greece and France to name a few.
In 2007, Zed Candy—an Irish confectionery company famous for its Chewing Gum—bought the brand from Donegal Creameries.
Until recently, the factory employed approx 15 people and up to 65 tonnes of sugar and chocolate confectionery were produced each week. The main production lines are Emerald, Toffees, Eclairs, Boiled sweets. The biggest sellers are Emerald, Colleen Assortment and Orange Chocolate.
The factory is due to be closed by the current operators, Zed Candy, on 27 May 2012. 
In May 2014 the factory was demolished.
The company's name is famously printed on many of its products including:
- Oatfield Chocolate Emeralds
- Oatfield Liquorice Toffees
- Oatfield Chocolate Eclairs
- Oatfield Irish Butter Toffee
- Oatfield Barley Sugar
- Oatfield Glucose Fruits
- "A History of Oatfield".
- Barrington, Kathleen (16 February 1999). "Donegal Creameries buys sweet maker". Irish Independent (Independent News & Media). Retrieved 16 February 1999.
- "About Us". Zed Candy.
- "Oatfield to close Letterkenny sweet factory". RTÉ News (RTÉ). 27 April 2012. Retrieved 27 April 2012.