Louis, 26, was a fourth-round pick by the Browns out of Auburn in 2016. He was entering the final year of his four-year rookie contract with Cleveland when they elected to cut him loose in April of last year.
He’s missed the last two seasons because of a neck injury suffered late in 2017.
Louis signed a one-year, $645,000 deal with the Dolphins shortly after being released by Cleveland and was set to be an unrestricted free agent.
In 2017, Louis appeared in 16 games for the Browns, catching 27 passes for 357 yards (13.2 YPC) and no touchdowns.