Established by selling clothing at country shows, the company established its own clothing line in 1999 and began to open shops in the 2000s. As of 2018, the company had 123 stores and a turnover of £185.9m.

Originally established as Joule & Sons in 1977 by Ian Joule, his son Tom took over the business in 1989. Joule & Son originally sold branded clothing and accessories at equestrian and country shows. Seeing a gap in the market for colourful country clothing as an alternative to traditional styles, Tom ordered 100 pairs of pink wellington boots to be manufactured, which sold out almost immediately.

In 1994, Joule & Son rebranded as Joules. The company's strategy changed to sell branded goods at minor fairs, and by 1997 had experienced success in selling branded outdoor clothing at bigger shows. In March 1999, Joules premiered its first clothing collection under its own name. In September 2000, Joules opened their first store next door to the café owned by his father in Market Harborough, Leicestershire. The company remains based in Market Harborough and its products are manufactured in China.[citation needed]

With the 2001 United Kingdom foot-and-mouth outbreak, almost all the shows that Joules intended to sell at were cancelled. In response, the company pivoted to selling clothing directly to retailers. The company's mail order catalogue business was launched in 2002, with its website following in 2003. Joules launched Little Joule in 2008, designed for 2–12 year olds. Following the popularity of Little Joule, Baby Joule was established in 2009.

Between 2003 and 2010, the company saw turnover increase from £3m to £50m, with mail order and internet sales accounting for a fifth of turnover by 2010. By early 2011, Joules saw its high street network rise to a total of 52 stores. During May 2016, Joules completed a successful stock exchange listing on the Alternative Investment Market.