It's a one-year, $2 million deal while incentives could boost it another $2.5 million, a source told ESPN's Adam Schefter.
Detroit brought in four veteran backs for visits over the past week -- Jonathan Stewart, DeMarco Murray, Frank Gore and Blount -- to try to fix a running game that ranked last in the league in 2017 in yards per game and yards per carry.
Blount, 31, led the Philadelphia Eagles with 766 rushing yards on 173 carries (4.4 average) and two touchdowns during the regular season. He saved one of his best performances for Super Bowl LII, running for 90 yards and a touchdown in a 41-33 victory over the New England Patriots, his former team with whom he won a ring in Super Bowl LI.
He is tied with Marcus Allen for sixth on the career postseason touchdowns list with 11.
Despite posting career highs in carries (299), yards (1,161) and touchdowns (18) with the Patriots in 2016, Blount remained on the market until the Eagles signed him to a one-year, $1.25 million deal last May. He proved not only to be an effective runner but was key in creating a loose locker room atmosphere and remained invested after losing snaps to Jay Ajayi, whom the Eagles acquired from the Miami Dolphins at the trade deadline.
In 116 regular-season games, Blount has rushed for 5,888 yards and 51 touchdowns.
After the season ended, Lions general manager Bob Quinn said he wanted to add at least one running back to the room after Detroit's struggles rushing. The Lions have gone four-plus seasons without a 100-yard rusher in a game, dating back to 2013. Blount had one 100-yard game last season.
"I think our running backs, you know, they didn't perform as good as everyone thought," Quinn said about his running backs in January. "I think that's the facts. But I think we have guys in that room that are tough guys, they're smart guys, they have skill. Will we add someone? Probably to that room, absolutely. But that's how the NFL really rolls. Every year there's about 30 percent turnover on teams, so you're never going to have the same team year to year."
ESPN's Tim McManus contributed to this report.