"Braxton Family Values" star Tamar Braxton is a mansion-flipping GODDESS ... just two years after buying her massive L.A. home, she unloaded the palatial digs for a $3.5 MILLION PROFIT.

Toni Braxton's lil sis bought the 11,700-sqaure-foot crib in Hidden Hills, CA with her husband -- bigwig record producer Vincent Herbert -- back in 2011 for $3.4 million. They listed the house in Oct. 2012.

Now for the kicker, the couple -- which just welcomed a newborn baby -- sold the pad earlier this year for ... wait for it ... $6.9 million!!!

Fun Fact -- the home is just a stone's throw from Justin Bieber's private community in Calabasas!