Lee Sang-chul, formerly head of the company's Russian operations, has been tapped as head of strategic marketing for the mobile business, a Samsung spokeswoman said.
His predecessor, Kim Seok-pil, stepped down from the role. A person familiar with the matter said Kim's decision was due to health reasons and was unrelated to performance. The executive is expected to return to work at a later time, the person said.
Lee, who also has worked as head of Samsung's Latin American operations, will be charged with overseeing the launch of the new Galaxy S device. The smartphone's success will be critical for Samsung, which saw mobile earnings slide 64 percent from a year earlier in October-December en route to a first annual profit decline in three years.
Analysts said Samsung cannot afford another premium smartphone flop after relatively poor sales of current flagship Galaxy S5. Recent research shows rival Apple Inc may have overtaken Samsung as the world's top smartphone maker in the fourth quarter.
The South Korean company has sent out invitations for a March 1 event in Barcelona - ahead of the Mobile World Congress trade show - where its next Galaxy S smartphone is widely expected to unveiled.