Kid Rock doesn't kid around when it comes to locking down his longtime gf ... we got the first shots of the diamond ring he put on Audrey Berry when he popped the question.

Sources close to the couple confirm they got engaged earlier this year, but rumors started swirling when Audrey was seen rocking this ring on her left hand during Kid's fan cruise a couple weeks ago.

No question, Audrey looked totally charmed by her rock ... she couldn't stop smiling and staring at it.

Audrey and Kid have been linked together for nearly a decade. This will be his second marriage. He famously married Pamela Anderson in 2006.