Amendola, who was set to become a free agent this offseason, amassed 62 receptions for 678 yards and one touchdown in his first campaign with the Lions in 2019.
The 34-year-old has now posted at least 55 catches and 500 receiving yards in each of the past three seasons. He played under a one-year, $4.5-million contract last year.
An undrafted player in 2008, Amendola made his regular-season debut for the then-St. Louis Rams in 2009. He then played in two Super Bowls during his time with the New England Patriots from 2013 to 2017, and the veteran spent a year with the Miami Dolphins in 2018 before arriving in Detroit.