Mathews was signed by the Dolphins on Thursday, Barry Jackson of the Miami Herald reports.
A BYU product, Mathews has spent time on the practice squads of the Chiefs, Browns and Vikings. It'll be a crowded competition for the No. 4 spot at receiver behind Jarvis Landry, DeVante Parker and Kenny Stills, but the 6-foot-5 Mathews has size on his side.
Mathews has been waived by the Vikings, Kyle Tasman of 247Sports.com reports.
Mathews signed with Minnesota in March but apparently failed to make much of an impression. His release cleared room for the addition of former Nebraska quarterback Tommy Armstrong.
Mathews signed with the Vikings on Thursday, Ian Rapoport of NFL Network reports.
Mathews signing adds depth to the Vikings receiving corps, though it is not clear that the 6-foot-5 wideout will clear final roster cuts in August. Mathews spent his college career at BYU, where he recorded 152 receptions for 2,083 yards and 24 touchdowns in 41 games. He spent last offseason with the Chiefs before joining the Browns practice squad for part of the regular season.