The Vikings also released receiver Maurice Mann to make room on the active roster for Johnson.
Johnson, a second-round draft pick by New England out of Texas A&M in 2003, never developed as an offensive threat for the Patriots and was traded to New Orleans this summer. The Saints cut him before the regular season started.
As a rookie, Johnson led the AFC with a 28.2-yard kickoff-return average. In his career, he has averaged 25.1 yards on 102 returns --
with two touchdowns. He has caught only 30 passes for 450 yards and
Henson, who starred briefly at Michigan and spent three seasons playing professional baseball in the Yankees organization, signed an eight-year deal with Dallas in 2003 that included $3.5 million guaranteed, but he never got his NFL career going.
He started only one game, in 2004, filling in for the injured Vinny Testaverde before Testaverde took over after halftime. Last year, Henson was the third quarterback behind Drew Bledsoe and Tony Romo. He was released by the Cowboys in late August and signed to the Vikings' practice squad on Sept. 27.
Minnesota (3-2) has a bye this week and take on Seattle on Oct. 22.