Denise Richards and Carmen Electra have never been on camera together... until now -- 'cause the two bombshells have shot a joint OnlyFans collab that will have fans sweating on Valentine's Day!

Carmen lit the fuse with a tit-illating (pun intended😏) IG pic Thursday teasing a V-Day collab -- and production sources tell TMZ the steamy shoot went down at the Creators Inc. mansion in Encino, California, with both stars in sexy lingerie and very into each other.

We're told they bounced from the bedroom to the living room couch in lingerie, and it got so steamy, they asked for a closed set -- but before you get too wild, we are told there was no kissing. Just a whole lotta tease!

Creators Inc.’s CEO Andy Bachman tells us, "“Denise Richards and Carmen Electra are two cultural icons who’ve never shared the same frame until now. They’ve each transcended traditional Hollywood and because they're forward thinkers, adapted to the creator economy  Now we're able to give fans an experience that they'll remember."

The full fantasy drops on their OnlyFans pages this Valentine’s Day -- consider it a love letter to your eyeballs!