Eich was born in 1961 in Pittsburgh, PA. Eich received a bachelor's degree from the University of Santa Clara County. In 1986, he received a master's degree from the University of Illinois at Urbana-Champaign.
Eich began his career at Silicon Graphics, where he worked for seven years. He spent the next three years at MicroUnity Systems Engineering.
In August 2005, after working as a chief technologist and a member of the board of directors of the Mozilla Foundation, Brendan became the technical director of the Mozilla Corporation, and on March 26, 2014, he was appointed an executive director.
However, already on April 3, he left this post in response to a protest by the US LGBT community (in particular, noted an appeal to OkCupid Firefox users) because in 2008 he supported the California bill banning same-sex marriage.
On January 20, 2016, the company released developer versions of its open-source Brave web browser, which blocked ads and trackers and included a micropayments system to offer users a choice between viewing selected ads or paying websites not to display them.
At Brave Software, Eich co-created the Basic Attention Token (BAT), a cryptocurrency designed for use in the Brave browser. BAT launched its ICO on May 31, 2017, and raised $35 million.