The Chiefs also promoted WR Marcus Kemp to their active roster.
Thompson, 25, is a former fourth-round pick of the Seahawks back in 2017. He was entering the final year of his four-year, $3.07 million contract when Seattle released him in March.
The Chiefs signed Thompson to a contract soon after.
In 2020, Thompson has appeared in eight games for the Chiefs and recorded 13 tackles and no interceptions.