Nguyen will join the agency in April, and will report to TBWA\Asia-Pacific's executive vice-president, Ian Thubron.
He replaces Juliana Nguyen in the role. She is leaving TBWA\Vietnam to return to her native Australia.
Before his stint at StrawberryFrog, George Nguyen spent time at agencies including DDB, Arnold and Lowe.
George Nguyen said: "Joining TBWA\Vietnam is an amazing opportunity to enter an exciting marketplace and a network that I have always had the utmost respect for."