Ballmer is joining Harvard President Drew Faust and Cherry Murray, dean of its School of Engineering and Applied Sciences, on Thursday to discuss further details of the initiative.
"We're so grateful for Steve's game-changing support and welcome this opportunity for the School of Engineering and Applied Sciences to take full advantage of the entire University's distributed strengths," Faust said in statement.
The SEAS, the newest of Harvard's 12 degree-granting schools, expanded from division status in 2007. The university said Ballmer's support will allow it to increase its computer science faculty by 50 percent.
Ballmer said in a statement that computer science "is the operating system for innovation at Harvard."
"Whether it's biology, history, public policy or medicine, the ability to help people get more done through CS is an area where Harvard has the resources and the perspective across those disciplines to be a leader," he said.
Ballmer earned a bachelor's degree at Harvard College in 1977, and joined classmate Bill Gates at Microsoft in its early years. He led the company from 2000 to 2014, and now owns the NBA's Los Angeles Clippers.