And he's dedicating the rest of his career to his memory.
Brent, 26, was convicted in January of intoxication manslaughter in the December 2012 accident that resulted in Brown's death. Brent, whose blood alcohol content was nearly twice the legal limit, was sentenced to 180 days in jail and 10 years' probation.
Brent spent nearly five months in jail. He spent the final 45 days of his sentence in a rehabilitation facility before being released this past summer.
The NFL reinstated Brent last month, and he's been practicing with the Cowboys for the past two weeks. His 10-game suspension ended after Cowboys' victory Sunday over Jacksonville.
"Honestly, to make sure Jerry's name does not die in vain," the defensive tackle said Wednesday afternoon as he spoke to reporters for the first time since his conviction.
"Jerry was a great person, a great player and had a bright future. A mistake that I made took that away from him, took that away from his daughter, took that away from his mother, so that's something that I make sure I keep, make sure I'm conscious of that -- never let his name die in vain."
Last week, Brent signed a one-year contract extension with the Cowboys that did not include a signing bonus. Brent said he understands how fortunate he is to get another opportunity to play in the NFL.
The Cowboys like Brent because he can provide size and strength to a defensive line that relies on speed and quickness. They think he can help them, especially against teams that want to run the ball between the tackles.
Cowboys coach Jason Garrett said Brent has been working hard to get in football shape but needs to lose some weight.
"I'm a very blessed person to be able to be in this position I am now," Brent said. "I'm just thankful that the commissioner, the Jones family and the Cowboys organization have allowed me to come back and be a part of this team.
"It's been very difficult. It's something that there's not an exact formula of how to be successful with this. It's just something I take daily and try to do the best I can."
Brent said the accident is rarely far from his mind, and his role in the death of his friend is something he's still learning to cope with daily.
"It's something that I've learned from, something I'll always remember every day of my life," Brent said. "I miss Jerry. That was my best friend, and to know that he's not here because of a mistake that I made, that could have been prevented, hurts me every day.
"So it's something once again I take day by day and keep it conscious on the forefront of my mind."
Cowboys vice president Stephen Jones said adding Brent to the roster is about giving Rod Marinelli another good football player to coach -- not just making sure Brent has a good support system.
"This is strictly about football. If we didn't think he could help us, we wouldn't have worked with him," Jones said. "That's a tough way of saying it, but the best 53 players make the team, and we think he's one of the best 53."