Beyonce's Mom & Dad -- Finally Divorced ... for Real This Time

Mathew and Tina Knowles' on again-off again divorce dragged on for two years, but it's now legally kaput, done, over ... final.

The final decree of divorce was issued last month in a Texas court, and according to documents -- obtained by TMZ -- Beyonce's mom refiled on August 30. Tina's first swing at the divorce was in November 2009 ... but the matter was dropped in 2010 when they were both no-shows for court.

In the docs, Tina says the marriage was "insupportable because of discord or conflict of personalities" ... which "prevents any reasonable expectation of reconciliation."

The papers make no specific mention of Mathew getting slapped with a paternity suit back in 2009 -- but the original divorce filing did come one month after that went down.

P.S. the kid turned out to be his.