"Mr. Cho Soo-in is the executive vice president of the memory division," a Samsung spokesman said.
Hwang Chang-gyu, who had been both president of the semiconductor business and head of the memory chip division, retains his semiconductor title, Samsung said.
Executive changes in the middle of the year are extremely rare at top South Korean companies.
Samsung reported on Friday its smallest quarterly profit in four years and its lowest operating profit since 2001 as steep declines in computer memory chip prices overshadowed improvements in flat screens.
Margins at Samsung's semiconductor division fell to 8 percent in the April-June quarter, from 12 percent in the first quarter and 22 percent in the year-earlier period, as overproduction led to price declines estimated at more than 40 percent in the second quarter alone.
The largest technology company outside the United States has also been at the center of media speculation that it might become the target of a hostile takeover.
The Chosun Ilbo on Friday quoted an unidentified high-ranking Samsung executive as saying the company had received information that U.S. billionaire investor Carl Icahn and other hedge funds were readying bids for the firm.
Samsung has said it was not aware of such a move and that it had a strategy in place to cope with a hostile bid attempt.