Anthony Weiner Sexting Partner -- Scores Six Figures ... To Sext

Anthony Weiner's sexting partner is making good use of her special skills ... scoring a low SIX FIGURE endorsement deal ... to keep on sexting.

Sydney Leathers inked the lucrative deal with IHookUp to be the face of their mobile phone dating app -- where locals find each other, text and then agree to hook-up. Pretty great.

As part of the gig Sydney will have to keep an active profile on the site, interact with users and possibly find people to canoodle with. Not exactly rocket science.

So why Sydney? A rep for the company tells TMZ, "It's all about that instant gratification and hooking up with the right person at the right time. Sydney seems to have that nailed down!"

Speaking of nailing things ... Sydney tells us, Weiner would have been a big fan.