The move will see the local beauty judge the final night of the beauty pageant, an event that will be virtually held on August 3.
This year has seen the Miss Philippines Earth 2021 attract the particiaption of 68 contestants from across the country.
The winner of the competition will succeed last year's winner, Roxanne Allison Baeyens, who later went on to be named as Miss Earth – Water in the Miss Earth pageant.
Phuong Khanh was born in the Mekong Delta province of Ben Tre in 1994 and became the second runner-up at the Miss Ocean Vietnam Global in April and Miss Earth 2018.
She stands at 1.7 metres tall, weighs 51kg, and has body measurements of 90-58-94 cm.