No corresponding roster move was announced, and team has not officially announced the signing.
Dobson, a second-round pick in 2013, was cut by the Patriots earlier this month. Last week, he worked out for the 49ers and Chargers.
New Lions general manager Bob Quinn worked for the Patriots before taking this job, so he has familiarity with Dobson.
Dobson, 25, has 53 career receptions and had four touchdown catches as a rookie. He participated in a workout Tuesday that also included former Lions running back Joique Bell.