Brent was convicted of intoxication manslaughter in January for his role in a December 2012 car accident that killed teammate Jerry Brown.
Brent, who did not play last season after announcing his retirement in July, was sentenced to 180 days of jail time and 10 years' probation. He spent the final 45 days of his jail sentence in rehab.
Brent can visit the Cowboys' practice facility after week 6, practice after week 9 and is eligible to play in games by week 11.
The 26-year-old recorded 31 tackles and 1.5 sacks in 39 games over three seasons in Dallas after being drafted in the seventh round of the 2010 supplemental draft out of Illinois.
- Chris Johnson