Rejlers was founded in Småland in 1942, and has been active as an engineering consultancy firm ever since. A common thread has run through our operations over the years: electrical engineering in various forms. Everything from nuclear power to electronics. Over the years, Rejlers has expanded into new areas of expertise such as telecommunications, mechanical engineering and IT.

In broad outline, the company's business has run alongside Sweden's development as an industrial nation. Initially, the company was active in the expansion of the electricity supply network in Sweden. After that, the company’s employees participated in the nation’s industrialisation and the mass housing initiative referred to as the Million Programme. Railway and telecommunications were added during the 1990s and 2000s. Environmental technology is being developed as a separate expertise during the 2010s. During the 2000s, Rejlers diversified geographically and has today operations in Finland, Norway and Russia.

The company was founded by engineer Gunnar Rejler in 1942. Since then the company has been managed by his son Jan and grandson Peter Rejler. Between the years 2012-2014 Eva Nygren was President and CEO. In April 2014 Peter Rejler re-entered as President and CEO until that Viktor Svensson took over the role in February 2018. The company has retained the character of a family business although its ownership base was expanded through a public share offering in 2003.