Rihanna turns 37 today ... and, we've got the "Pon De Replay" of all her sexiest snaps to celebrate the momentous milestone.

The singer-songwriter's not afraid to strip down to her skivvies for any reason ... often getting into her lingerie to promote her products or just to feel the breeze on her behind.

Whether it's all-black undies, or a stylish pair with some color in the shape of rainbows dotting her chest and hips, RiRi always brings her A-game to fashion.

And, occasionally, Rihanna likes to strip down to nothing at all ... placing a strategic arm over her nipples to pique the interest of her excited fans.

Rihanna got an early birthday present for her 37th ... as you know, her partner A$AP Rocky was found not guilty on two charges of assault with a semiautomatic weapon in L.A. this week.

Rocky dove into Rihanna's arms after the verdict ... and, the two went out and grabbed dinner together in the evening to celebrate.

So, looks like Rihanna couldn't ask for a better present ... and, her fans are sure to think the same of these hot shots!