McGee was CEO from Oct. 1, 2009, through July 1, 2014, leaving as his struggle with cancer worsened. He served as chairman until Jan. 5.
The illness was first disclosed to the public in January 2013, when the company said McGee had a brain tumor surgically removed and that he was receiving low-dose chemotherapy.
He recently relocated to southern California, though some executives at The Hartford were in regular contact with him.
The company announced his death on Monday morning to employees and the public. Also on Monday, the company put up a tribute page to McGee on an internal website for employees with space for people to share their memories. The company is working on additional plans to remember McGee.
"Liam was a man of commitment, integrity and compassion, and we were fortunate to have him join The Hartford during a challenging time in the company's history," Thomas A. Renyi, presiding director of The Hartford, said in a statement. "Liam made the tough decisions necessary to guide the company through this period, with an unwavering focus on what was best for our company, our customers, our employees, our shareholders and our community."
McGee was born in County Donegal, Ireland, and grew up in southern California, the son of Irish immigrants. His father was a bus driver in Los Angeles and progressed to management at Southern California Rapid Transit.
McGee graduated from the University of San Diego in 1976 with a bachelor's degree in biology. He played baseball for the university, wrote for the student newspaper and was active in student government. He went on to earn a master's degree in business administration from Pepperdine University and a law degree from Loyola Law School in Los Angeles.
During college, McGee worked as a bank teller, foreshadowing to his long career in financial services. He was an executive at Bank of America Corp., where he oversaw more than 5,000 branches as president of the Consumer and Small Business Bank. Before Bank of America, he worked in various senior positions at Wells Fargo.
"Liam was a true visionary," Ken Lewis, former Chairman and CEO of Bank of America, said in a statement. "He had ideas about how things should be and would be in the future that were special and unique to him. He had an amazing ability to convey that vision; help others see their role in it and follow his leadership to achieve amazing results.
"We gave him huge challenges at Bank of America and had high expectations for what he would do," Lewis said. "He exceeded those high expectations every time and left an indelible imprint on all with whom he worked. Liam was my good friend; a man I admired. I will miss him greatly."
McGee arrived at The Hartford in the fall of 2009, after a low point in March when the company's stock fell to $3.62 from a peak of $106 in May 2007. The Hartford lost huge sums on investments during the economic downturn, was over-extended on its variable-annuity business, and suffered downgrades of its financial health ratings.
The company received $3.4 billion in federal stimulus money before McGee arrived, and he made a point to repay the federal government within the first six months he was on the job.
Two years after repaying the government, in March 2012, McGee announced a major transformation that called for an end to new sales of annuities. The company also sold off large business segments: Individual Life, Retirement Plans and its Woodbury Financial Services brokerage. At the time, McGee said The Hartford wanted to have superior performance, and the status quo was not going to let the company get there in a "reasonable period of time."
Since the spring of 2012, the company has focused on property-casualty, group benefits and mutual funds, which are considered more profitable and less volatile businesses than the other segments The Hartford chose to divest or to discontinue.
He stepped down as CEO in July 2014 amid continuing health problems and was succeeded by Christopher Swift, who was the chief financial officer.
During McGee's tenure at The Hartford, the company invested in the city of Hartford and the Asylum Hill neighborhood, where the 205-year-old company has been headquartered for almost 100 years. Under McGee, the company dedicated $7 million over five years to address blight, rebuild homes and provide various other services.
Gov. Dannel P. Malloy said, "Liam set two missions when he came here, saving a great American company and improving the city in which it is headquartered. He accomplished both."
U.S. Sen. Richard Blumenthal, D-Conn., said in a statement: "Liam was a community and business leader of hugely impressive integrity, intellect, dedication, and grace - who gave me his views and advice with an incomparable combination of charm and candor. From our first lunch to my last visit to his office at The Hartford, he was unstintingly generous in his friendship, and his clear caring for the people who worked with him."
A Mass of Christian Burial will be celebrated on Feb. 24 at Saints Simon and Jude Catholic Church in Huntington Beach, Calif. A private burial will follow.