A Dallas County jury deliberated about 10 hours over two days before the announcing the verdict, in which Brent was found guilty of drunken driving and crashing his car, resulting in the death of his friend and teammate.
Brown -- a linebacker on the Cowboys' practice squad -- was a passenger in Brent's car when it struck a curb at a high rate of speed and flipped over in Irving, Texas, after the two left a Dallas nightclub in December 2012.
Brent could face as much as 20 years in prison. The jury is set to reconvene Thursday to determine his sentence.
Police said Brent's blood alcohol level on the night of the crash was .189, more than double the legal limit. His lawyers, however, challenged the validity of the results, contending Brent spoke clearly, without slurring his words, in the 911 call he made after the accident.
Prosecutors showed footage of Brent's failed field sobriety test, WFAA-TV, Dallas, reported.
Brent appeared in 44 games over three seasons with Dallas from 2010-12, and has not played in an NFL game since the accident.