It took 8 months, but Cardi B and Offset are finally revealing their baby boy's name and showing him off to the world -- so get ready to meet Wave Set Cephus!!!

The proud parents both posted pics Thursday of their little bundle of joy, already iced out in Cuban link chains ... with Offset revealing the unique name in the caption.

Cardi posted a different shot of her son ... wearing a baby blue puffy jacket, and you can see Wave Set has a huge iced-out pendant hanging off those Cuban links.

Don't worry ... he'll grow into it.

For the big reveal, the proud parents gathered the whole fam for an Essence photoshoot.

Remember, Cardi gave birth to WS back on Sept. 4, but she and Offset kept the kid's name as secret as the White House nuclear codes.

Back in October, we got Cardi at LAX ... and while talking to us about Offset's upcoming birthday she almost slipped and dropped Wave Set's name. Almost!!!

This is the second child for Cardi and Offset, and his big sister Kulture is now 3-years-old.

Offset also has 3 other children from previous relationships ... 11-year-old son Jordan, 6-year-old son Kody and 6-year-old daughter Kalea.

Apologies to everyone else in the Offset and Cardi's household, but Wave Set might have the coolest name in the fam. Maybe the whole country!