MTV News reports that a billboard featuring the stars will be unveiled in Los Angeles today, as part of PETA's 'Fur-Free and Fabulous' series.
The organisation - who criticised GaGa's meat dress for last year's MTV Video Music Awards - said in a statement: "Her anti-fur stance... has been unwavering. GaGa's out-there outfits never include real fur.
"Last year, when she wore a dress made of fluffy Kermit the Frog dolls, [she] explained, 'I thought it was [a] commentary on not wearing fur, 'cause I hate fur and don't wear fur.'"
The organisation added that Pink and Carey were chosen due to their long-standing commitment to challenging the fur trade.