Kunnath, who had joined the Bangalore-headquartered company in May 2012, has resigned to pursue another opportunity, OnMobile said in a statement.
His resignation will be effective March 28, 2014, it added. The BSE-listed firm will immediately commence a search for a new CFO.
"On behalf of the company and the Board of Directors, we thank Rajesh for his contribution to the company during his stint with us and wish him the very best in the next phase of his career," OnMobile Chairman H H Haight said.
Kunnath served as the CFO of Times Internet Ltd and has also worked at Heinz India, Hindustan Lever and ABB.