He received support from all 440 deputies present at the voting, equivalent to 91.6% of the 500 total deputies.
Luong, 67, is serving as director of the political department of People's Army since 2016, Turkish Anadolu news agency reported.
He is a member of politburo of the Communist Party of Vietnam as well as standing member of the Secretariat, and a delegate to the 15th National Assembly.
This ends the dual role of To Lam, who was elected as president in May to replace Vo Van Thuong, who stepped down on allegations of corruption. He became the general secretary in August after the death of Nguyen Phu Trong.
In the Far East country's one-party political system, the president is one of the top four positions besides the general secretary, prime minister and chairman of National Assembly.
MA/PR