Phuong Khanh Nguyen was the official representative of Vietnam in Miss Earth 2018 and she was crowned as the winner at the end of the competition. Since she was 15 years old, Nguyễn had an inclination towards the Miss Earth competition and it was after three years, in 2018, she vied for the crown of Miss Earth Vietnam 2018 and ended up being crowned. Fulfilling her duty as Miss Earth Vietnam 2018, the diva went on to win the crown of Miss Earth 2018, labeling herself as the first Vietnamese woman to win the title. Upon returning back as Miss Earth 2018, she was welcomed and embraced by her people and her victory was celebrated as if it was a Vietnamese festival. The beauty, in 2019 was designated as the Ambassador of the Earth Hour 2019 to promote the event and to implement several environmental protection activities. As an ambassador, she urged everyone not to waste energy by switching off unnecessary lights and household equipment for an hour. She also collaborated with various Vietnamese actors and shared an article on how people can help prevent the Amazon forest from being destroyed by the massive fires that broke out in 2019. She fulfilled her duties as Miss Earth 2018 and traveled to different countries including Colombia, United States, China, France, Belgium, and Germany.