Tahiti's Rossi and Matauli of New Caledonia triumphed in the respective men and women's badminton contests at Samoa 2019.
Rossi also clinched gold in the men's doubles and mixed doubles events.
With the support of the Badminton World Federation (BWF) Badminton Oceania has now announced the pair as ambassadors for "i am badminton".
The campaign was launched by the BWF in 2015 and is the vehicle for sharing knowledge and communicating the integrity function in badminton.
“I am eager to promote clean and fair play,” said Rossi.