Cardi B and Offset Secretly Married Last Year

1:22 PM PT -- Cardi just opened up about the wedding, saying, "There are so many moments that I share with the world and then there are moments that I want to keep for myself! Getting married was one of those moments! Our relationship was so new breaking up and making up and we had a lot of growing up to do but we was so in love we didn't want to lose each other."

She continues, "I said I do, with no dress no make up and no ring! I appreciate and love my husband so much for still wanting for me to have that special moment that every girl dreams of when he got down on his knee and put a ring on my finger and he did that for me!!

Cardi B and Offset are already married, and documents show they actually tied the knot MONTHS ago -- which explains why he's now calling her his "wife" in public.

We did some digging and found out they got a marriage certificate in Fulton County, GA on Sept. 20, 2017. For you single folks ... the marriage certificate is filed with the court AFTER a couple does the deed as proof the marriage really happened.

When Migos won Best Group Sunday at the BET Awards, Offset said excitedly, "I thank my wife. You should thank yours."

The secret marriage puts a new perspective on their big public engagement. You'll recall, Offset got down on one knee back in October during their performance in Philly.

Turns out ... Offset and Cardi are a true showbiz couple 'cause that was all for show. Now, we know they were already husband and wife for a month at that point.