Hockenson, the team's first-round pick last season, had 32 catches for 367 yards and two touchdowns in his rookie season before suffering a right ankle injury on Thanksgiving against Chicago that ended his year.
The Lions are counting on Hockenson to play a pivotal role in his second year as the team's top tight end, paired with Jesse James.
The Lions have slowly returned to health after having eight players land on the COVID-19 list in the first week -- including quarterback Matthew Stafford, who ended up with a false positive that helped lead to alterations to the NFL's testing protocol. Stafford was activated Tuesday.
In addition to Hockenson, cornerback Amani Oruwariye and punter Arryn Siposs were also activated from COVID reserve on Saturday. Oruwariye is in line to be Detroit's top depth cornerback. Siposs, a former professional Australian Rules football player who then went to Auburn, is competing for the team's punting job with Jack Fox.