The nine-time Grammy winner is behind the British songstress all the way at the prestigious US music ceremony, for which Adele has received six nominations.
"Wow, I'm such an Adele fan and I love what she has done this year. Her album was amazing, she's amazing and I'm just rooting for her," Mary said on the red carpet of the (Belvedere) RED pre-Grammy party in Los Angeles.
"I'm looking forward to seeing everyone, but I'm just rooting for Adele. I keep saying it because she's a real singer, she sings from the heart, she's young and that's so rare. You just really want that one person to get what they deserve finally, and not give it to someone else - just win all six of her awards," she added.
Mary performed at the glittering night, which saw X Factor judge Tulisa Contostavlos, Kelis and actress Malin Akerman step out for the party, hosted by Belvedere vodka in support of the (RED) Foundation.
"It's important to team up with Belvedere and (RED) Foundation... (AIDS) hasn't disappeared and more people need to be aware that it still exists," Mary said.