Primark was started in Dublin, Ireland in 1969 by the Westom family. After its success as Penneys, it expanded into other countries. The company now has 345 retail stores located in eleven countries across Europe and the rest of the world, including the UK, the Republic of Ireland (trading as 'Penneys'), Portugal, Spain, Germany, the Netherlands, Belgium, Austria, France. Italy and the U.S.
Over the last 10 years, Primark has increased its share of the UK apparel market by more than 2.5 percent. As of 2018, it ranked is the second largest clothing retailer in the UK, following Marks and Spencer, with a market share of approximately seven percent.