Online newspaper VietnamNet said Jackson, 82, was at the groundbreaking as one of the investors in the $2 billion, five-star 1,000-room hotel and amusement park in southern Long An province, located about 20 minutes outside Ho Chi Minh City. It is scheduled to be finished in 2014, and is designed to attract up to 14 million visitors annually.
"I like discovering different cultures in the world," VietnamNet quoted Jackson as saying. "I like this project the most because it is located in a beautiful cultural and natural space."
Vietnam has promoted the project - which includes a water park, theaters and restaurants - as the region's largest entertainment complex.
Pop icon Michael Jackson, 50, died in 2009 from an overdose of the powerful anesthetic propofol and other sedatives. His doctor has pleaded not guilty to charges of involuntary manslaughter.
Michael Jackson was known for his creation of Neverland Ranch, a huge complex complete with an amusement park, in California where he lived.