Barra takes over as chairman from former Cummins Inc chief executive Theodore Solso, who will continue serving as the board's lead independent director, the company said.
GM has over the years swung back and forth on the issue of whether the CEO and chairman's jobs should be held by different people. In the early 1990s, after a close brush with financial collapse, GM's board separated the two jobs in a move hailed by corporate governance experts.
Barra's appointment as GM's chief executive in 2014 made her the first woman to lead a major automaker. But almost immediately upon taking over, Barra was hit with the fallout from a scandal over long-delayed recalls of GM cars with a potentially deadly ignition switch defect.
Much of her first year as CEO was spent dealing with that crisis. Among other moves, Barra agreed to set up an independent fund to compensate victims of accidents involving cars with defective switches.
GM in September paid US$900 million to settle a Justice Department criminal investigation. Experts said Barra's decision to bring in an independent investigator and take a number of steps to overhaul GM's handling of safety problems and provide more information to regulators helped limit the size of the penalty.
In early 2015, a shareholder group challenged Barra over GM's management of its growing cash hoard. Barra reached a deal in March under which GM agreed to return US$10 billion to shareholders in stock buybacks and increased dividends by the end of this year and commit to hitting certain financial targets, including generating a 20 percent return on invested capital.
In October, GM reported record third-quarter profits and projected it will hit its major financial targets for the year, including a 10 percent profit margin in North America. Booming US sales of trucks and sport utility vehicles have helped GM weather weak results in Latin America and Europe and a slowdown in China.
In a related development, GM will invest US$500 million in Lyft Inc and laid out plans to develop an on-demand network of self-driving cars with the ride-sharing service.
The biggest single Detroit-Silicon Valley crossover deal to date comes as automakers work out how to respond to the rush of technology companies such as Apple, Alphabet and Uber - Lyft's biggest rival - to control cars of the future and likely reshape the global auto industry.
GM's investment accounts for half of Lyft's latest US$1 billion fundraising round. It is one of GM's biggest investments in another company and the largest single cash injection to date by a traditional automaker into a young technology firm.
The two companies said the partnership was based on the shared view that self-driving cars will first reach consumers as part of a ride-sharing service, rather than vehicles owned by drivers.
