McEwan, 56, who joined the company a year ago to run the bank's retail arm will take over from Stephen Hester, who led the bank following its £45 billion taxpayer buyout.
He will receive an annual salary of £1 million and will also receive a cash allowance in lieu of a pension totalling 35% of his salary.
While he is eligible to receive a long-term incentive award in 2014, McEwan said he does not wish to be considered for an annual bonus in 2014 or for the remainder of 2013, a statement from the bank said.
Chancellor George Osborne welcomed the appointment and said McEwan had impressed with his vision of RBS "as a strong, UK-centred corporate bank", focused on supporting the British economy.
"I think he'll provide the leadership RBS needs as the bank puts the mistakes of the past behind it, and the Government seeks to get the best value for the taxpayer from the money the last government put into the bank," Osborne said.
RBS chairman Philip Hampton said McEwan's leadership skills and extensive experience in banking will make him a success.
Ross has already become a champion for customers in our business and will continue that role as CEO," said Hammond.
"This is a job that is among the most important and challenging in the business world, and Ross has shown that he has the drive and capability to take it on.
McEwan will begin his role on 1 October.
