Clarke was an adviser on national security to several U.S. administrations.
"In addition to his invaluable public service keeping our country safe and secure, Dick has an incomparable vantage point when it comes to national and homeland security," said SRA President and Chief Executive Officer Bill Ballhaus.
"His insights will be a key asset for SRA clients and further strengthen our cybersecurity and counter-terrorism offerings."
In addition to his posts in government service, Clarke has written several books, including "Against All Enemies: Inside America's War on Terror," and "Cyber War: The Next Threat to National Security and What to Do about It."
"I'm pleased to be joining SRA, having long admired its ethic of Honesty and Service and focus on delivering value and thought leadership to government clients," Clarke said. "I've been impressed by the breadth and depth of SRA's cybersecurity team and look forward to contributing to their efforts."