Energy UK said in a statement on Thursday that Knight is leaving the high-profile post to “develop further a non-executive portfolio career”.
Knight said she would not lose her interest in the sector but would continue to pursue these interests in a non-executive capacity.
“It has been a great two years bringing Energy UK together to support and represent at such an important time, this industry that is so vital to the country,” Knight said.
“Building new, cleaner and greener electricity generators and making the other changes necessary to meet national and international targets inevitably adds to customers’ bills. At the same time, consumers expect a first class service from the industry, a secure energy supply and one which is affordable,” she said.
Knight described Energy UK as being “at the heart” of the current energy debate over how the energy sector changes are brought about and consumer expectations are met.
“I will be handing over a strong organisation capable of the task,” she added.