He will support the technology firm's business and external engagement initiatives in collaboration with CEO Arvind Krishna and other corporate executives, IBM said Tuesday.
Cohn led the National Economic Council and served as assistant to the president for economic policy from January 2017 to April 2018.
"Gary is a globally respected leader with deep experience operating at the center of business and government," said Krishna. "As a senior representative of IBM, his knowledge of technology and business transformation, combined with policymaking expertise, will bring unique value to our clients and stakeholders as we accelerate our hybrid cloud and AI strategy."
As Cohn Robbins Holding Corp.'s co-chairman, Cohn helps spearhead the special-purpose acquisition company through investment efforts in the cybersecurity, blockchain and medical and regulatory technology areas.
He was president and chief operating officer at The Goldman Sachs Group from 2006 through 2016 before he joined the White House as President Donald Trump's chief economic adviser.
His other current roles include serving as a member of the Federal Deposit Insurance Corporation's systemic resolution advisory committee, board chairman at Pallas Advisors and a board member at Abyrx, Indago and Gro Intelligence.