Hooi Ling, who co-founded Grab with CEO Anthony Tan in 2012, will transition into an advisory role, the company said.
Her succession plan has been in place for a while, Tan wrote in an internal memo to employees, adding that Hooi Ling will also give up her board directorship.
"People who know me well know that I am an adventurer at heart, and there are many other personal passions that I have put aside to build Grab with Anthony," Hooi Ling said in a statement.
"With the strong leadership bench we currently have, I believe now is the right time for me to pass on the baton to our next generation of leaders, and to pursue these other passions."
Tan and Hooi Ling developed Southeast Asia's biggest ride-hailing and food delivery firm from an idea for a Harvard Business School venture competition in 2011.
In the memo, CEO Tan said that Hooi Ling will not be replaced immediately. The nominating committee will consider candidates to supplement the board only later this year.