The 37-year-old Freeney became available after the Seattle Seahawks waived him Tuesday following a four-game stint with the club during which he had three tackles and three sacks.
The Lions will be the sixth team Freeney has played for in his career -- and this will mark the first time he has been on two teams in one season.
The move also reunites Freeney with Lions coach Jim Caldwell, who coached him in Indianapolis from 2009 to 2011. Freeney was a Pro Bowler in every season he played under Caldwell, and a first-team All-Pro in 2009.
Lions team president Rod Wood said on WJR radio that Freeney will play as soon as he's ready. The team hosts the Vikings on Thursday.
Seattle signed Freeney last month, adding him to a defensive line rotation that had lost Cliff Avril to injured reserve. Freeney recorded a sack in his Seahawks debut, then two more the following week. He averaged 28 snaps over his first three games, then played 17 in Seattle's 34-31 loss to the Atlanta Falcons on Monday night.
Speaking Wednesday, Seahawks coach Pete Carroll called the decision difficult.
SANTA CLARA, Calif. -- San Francisco 49ers coach Kyle Shanahan gave plenty of thought throughout the bye week and into the start of this week to changing quarterbacks from rookie C.J. Beathard to Jimmy Garoppolo.
After careful consideration of Garoppolo's status as a relative neophyte in his offense and how well Beathard played in the Niners' most recent game, a 31-21 win over the New York Giants that marked their first victory of the season, Shanahan is sticking with Beathard for at least one more week.
Shanahan announced Wednesday that the plan for Sunday's game against the Seattle Seahawks will be the same one the Niners have used in the weeks since Garoppolo's arrival with Beathard as the starter and both quarterbacks being evaluated for their work in practice throughout the week.
"I don't see it much different than other weeks," Shanahan said. "I plan on starting C.J. this week. As always, we'll see how practice goes, just like we would with any other position. But reps-wise and everything, we see the same this week as it's been."
With a bye last week, the Seahawks game had seemed like the most logical time for Garoppolo to step into the starting lineup. The Niners were able to use the time off to get healthier; Garoppolo had a chance to get more familiar with the offense; and their next game was at home against a familiar opponent.
But what seemed like a sure thing changed Nov. 12 when Beathard threw for 288 yards on 19-of-25 passing with two touchdowns and an interception for a passer rating of 123.4. He also rushed for a touchdown that helped seal the Niners' first victory of the year.
Benching Beathard after that performance and a victory proved to be a prominent factor in Shanahan's decision to stick with him for another week.
"C.J. did play his best football last week, which definitely, to me, made the decision easier," Shanahan said. "It wasn't just C.J. but the offense around him, everyone together. I thought that group of 11 guys when they were out there, they had their best game and that was important for C.J. It was also important for our team.
"I did go into the weekend and all week and into Monday considering Jimmy, but definitely, the way that game went, I knew it was going to make it easier for me to stick with what we've been doing, because I think we've made a stride in that way and I don't think it's totally right for Jimmy, C.J., the entire team and organization just to change that right away."
Aside from Beathard's performance against the Giants, Shanahan's decision also largely came down to how far Garoppolo has come since he arrived in the trade the Niners and New England Patriots
Dwight Freeney had been productive during his short time with the Seahawks so why waive him? Some potential reasons and a look ahead.
The Seahawks announced the move Tuesday.
Seattle signed the 37-year-old Freeney last month, adding him to a defensive line rotation that had lost Cliff Avril to injured reserve. Freeney recorded a sack in his Seahawks debut, then two more the following week. He averaged 28 snaps over his first three games, then played 17 in Seattle's loss to the Atlanta Falcons on Monday night.
The Seahawks did not announce a corresponding move, so their 53-man roster has an opening. The Seahawks still have 10 defensive linemen on their roster, so the move to waive Freeney could be to clear a spot for a player at another position.
It will also save Seattle some needed cap space. Freeney's deal was worth a prorated share of $1 million and included roster bonuses worth $8,000 for each game he was active, according to ESPN's Field Yates. The Seahawks have the least amount of cap room of any team in the league, according to the NFL Players Association website, which lists the figure at $150,505.
A deal with Freeney had been in the works for a few weeks before the Seahawks signed him in Week 8 to boost their pass rush. Their interest in him began in earnest when Avril suffered a neck injury in Week 4 that landed him on IR.
Seahawks defensive coordinator Kris Richard praised Freeney last week for the impact he had made on the field and also said his presence has helped Seattle's other defensive linemen.
"Dwight's awesome," Richard said last week. "He had a couple of games back there to where he kind of lit it up, and he was the Dwight of old. Nevertheless, it's really about what he's giving to the other guys, which is kind of the best of his nature. What made him so successful is his preparation, the way he takes care of his body, the way that he prepares out there on the field, obviously, his practice habits, and things like that. Those are the things that he's able to share, so when he gets out there in the football game, it's what he does. It's another day at the office for him, and that's kind of what we've seen. This is what he does, and he's a true professional."
Freeney is 17th on the NFL's all-time sack list with 125.5, which is second among active players behind Julius Peppers
Mike Davis is extra motivated to make it back in time to face San Francisco, the team that drafted him in 2015, but that could be a stretch.
When it comes to trick plays that failed spectacularly, the Seahawks don't have the market cornered. Just ask the 2015 Colts, who set that bar high.