The 32-year-old royal was joined by the "Work" singer in her native Barbados for World AIDS Day on Thursday to raise awareness for the fight against HIV/AIDS.
"Watch Prince Harry and @Rihanna test for HIV, to show how easy the process is #WorldsAIDSDay #RoyalVisitBarbados #ProTESTHIV," the royal palace tweeted, along with a video of the two undergoing the test.
This is the second time this year Prince Harry has been tested on behalf of the cause, after the royal was tested via Facebook Live at the Guys and St. Thomas’ Hospital in London this past July.
Harry first joined RiRi on Wednesday during the Barbados stop of his Caribbean tour to celebrate the island's 50th Anniversary of Independence with a concert and fireworks show, along with a ceremonial monument unveiling.
Watch the video below for more.