Beckers will take over the new position on April 1, Cosmote Romania said in a press release Tuesday.
The two mobile operators are owned by Greek group OTE.
Theocharopoulos will take on new responsibilities within OTE Group as Group Chief Technology & Operations Officer for both fixed and mobile telephony, the company said.
Beckers began his career in 1989 at Deutsche Bank and also served as President and CEO of Deutsche Telekom France, Managing Director of Deutsche Telekom Philippines, Financial Director at T-Online France. He was appointed T-Systems France CEO in September 2011.
Theocharopoulos joined OTE Group in 2002. He was named Cosmote Romania CEO in January 2008 and Romtelecom CEO in July 2011.
Cosmote Romania and Romtelecom registered cumulated turnover of about EUR1.2 billion in 2012.