The singer and entrepreneur, 32, said the Hello star, also 32, looked “incredible” both before and after she managed to lose an incredible seven stone.
But, Rihanna added, she’s overjoyed to see her mate looking so “confident and content” after adopting a rigorous training regime.
“Adele looked incredible before the transformation and she looks incredible now,” Rihanna enthused, “but you can see how happy she looks.
“It’s obvious the transformation was for her and not to impress anybody – and I am just happy that my friend looks so confident and content.”
Rihanna and Adele have been close friends for a decade now, the former gushing in 2012 that she hit up the BRITs ceremony in London to “stalk Adele”.
“It was nothing about the awards or the performance,” she laughed, “for me it was just to see Adele again.
“She doesn’t know the depth of my affection. She has no idea. The last album 21 spoke to me so much.”
And Adele is equally starstruck by Rihanna, writing in a short essay for Time magazine : “I actually can’t remember the first time I met Rihanna; I was probably numb from the shock of it…
“Whenever I’ve met her, she’s been the most gracious, loyal and funny goofball of an icon. She glows like when someone’s taken a picture with a flash and you’re dazed for a few minutes after.
“But it’s also very clear in that glow that she genuinely doesn’t give a f**k; she’s fearless and full of all the right kind of attitude to be everything that she is and will be forever.”
Since her weight loss, speculation has been rife about how Adele did it.
Adele’s personal trainer recently shed some light on her transformation, saying the proud mum wanted to get healthy for the sake of seven-year-old son Angelo.
She shares the little lad with ex-husband Simon Konecki, who she split from last year.
Sticking to a rigid workout and diet regimen, Adele also binned the junk food and booze.
She’s also thought to regularly chug down green juices to keep her system in tip-top shape.