A source told ESPN's Dianna Russini that the deal is for one year, $4.5 million and could be worth up to $5.75 million.
The Lions need a slot receiver after trading Golden Tate to the Philadelphia Eagles at the trade deadline last year. Amendola has 391 catches when lined up in the slot since his first full season in the NFL in 2009, the second-most in the NFL in that time behind Wes Welker, according to ESPN Stats & Information.
In their search for a replacement for Tate, the Lions had gone through Bruce Ellington, TJ Jones and Brandon Powell. Of the three, only Powell, an undrafted free agent from Florida last year, is signed by the Lions for 2019.
The signing also reunites Amendola with Lions general manager Bob Quinn and coach Matt Patricia from their time with the New England Patriots.
Amendola, 33, continued to show his toughness and knack for finding open zones out of the slot with the Dolphins, leading the team in receiving last season with 575 yards on 59 catches.
He was released Friday, as the Dolphins didn't see him as a long-term fit at his price for a team that is in rebuilding mode, although they did like the leadership that he brought to the locker room in his only season in Miami. The Dolphins saved $6 million in salary-cap space by releasing Amendola, who signed a two-year deal last March for $12 million.
An 11-year veteran, Amendola has had a nice career after starting as an undrafted free agent out of Texas Tech in 2008. He has caught 485 passes for 4,684 yards and 20 touchdowns while also playing for the Rams and Patriots, with whom he won two Super Bowl rings but left for a bigger payday after taking pay cuts in each of his final three seasons with the team.
Amendola's time in New England, from 2013 to 2017, overlapped with Patricia's time as defensive coordinator and part of Quinn's time with the club.
Amendola, who started more than eight games for the first time in his career last season, has played 16 games in a season just twice (2010, '14).
ESPN's Michael Rothstein and Cameron Wolfe contributed to this report.