Rihanna Looked Stunning at Her Best Friend's Wedding in Barbados

Rihanna's never one to play second fiddle ... unless of course she's at her best friend's wedding.

RiRi hit up Barbados over the weekend where she was a bridesmaid at her best friend Dr. Sonita Alexander's wedding. Rihanna couldn't help but throw her hands in the air when she made eye contact with her BFF, who also raised her hands while riding in a 1960 MGA Coupe driven by her father.

The Barbados Babe -- who has known Sonita since they were 11 -- wore the hell outta this blue dress in yet another example that her wardrobe's got serious range.

BTW, remember this badass pose? She was a bridesmaid back in 2015 at another good friend's wedding in Hawaii. She was front and center ... cig hangin' from her lips.