The Tullamore Distillery was founded in 1829 by Michael Molloy in Tullamore, County Offaly, a region known for its grain production. Tullamore DEW whiskey was later produced by Irish Distillers in Midleton, where modern production facilities and high quality standards were utilised.

Since 2010, the brand has belonged to the Scottish distillery group William Grant & Sons, which also owns Glenfiddich. Today, the whiskey is produced in a modern distillery near Tullamore, which was opened in 2014. This facility combines traditional production methods with modern technology to ensure the high quality of Tullamore DEW whiskey.

Tullamore Dew's 12-year-old Special Reserve is a blend of whiskeys matured in old bourbon oak casks and sherry casks in which Oloroso sherry was previously stored. Its speciality lies in the high proportion of pot still and malt whiskeys compared to grain whiskey. All components of the blend are triple-distilled and have a minimum age of 12 years