Higgins graduated from the United States Naval Academy with a Bachelor of Science degree in nuclear science in 1966. Eleven years later he was given a Master of Business Administration degree from the George Washington University. Also Walter attended the University of Idaho, which graduated in 1979.
Higgins began his career as a technical assistant at the United States Nuclear Regulatory Commission in 1975, where he worked until 1977. Then he held various management and executive positions at Portland General Electric Company from 1977 to 1991. Two years later Walter served as a chairman, chief executive officer and president of Sierra Pacific Resources (nowadays NV Energy) and held it until 2007. Also in 2000 he took a position of a director of at the same company, where he worked until July 31, 2008.
Since October 2009 he was a director of GTO Resources Inc. In addition, since November 22, 2010, Higgins served as a director of South Jersey Energy Company and has been its Lead Independent Director. He worked as the lead director and director of Emergent Capital, Inc. from February 7, 2011 until July 18, 2012.
Also in May 2012 Higgins was appointed a director, president and chief executive officer of Ascendant Group Ltd. and held the position until October 2016. He was a president and chief executive officer of Bermuda Electric Light Company Limited from September 2012 until October 2016. Walter has been a chief executive officer of Puerto Rico Electric Power Authority since March, 2018.
Higgins is a chairman of the Board of Trustees of the National Environmental Education and Training Foundation, director of Training Foundation, Edison Electric Institute, Western Energy Institute and several not-for-profit organizations. Also he is a trustee of the Foundation of Saint Mary's Hospital of Reno, the Nature Conservancy of Nevada and Sierra Nevada College Foundation.