Ex-NBA star Sebastian Telfair has been sentenced to 3 1/2 years behind bars for possessing an illegal firearm in 2017 ... TMZ Sports has learned.
As we previously reported ... the 33-year-old former high school phenom was busted back in June 2017 in Brooklyn .... after cops found an arsenal of weapons in his car during a traffic stop.
Officials say the former Trail Blazer, Celtic, Clipper and Timberwolf (to name a few) had 3 pistols and what appeared to be a semi-automatic rifle.
Telfair was convicted of one count of second-degree criminal possession of a weapon back in April .