Johnson elected to become a free agent Thursday, Matt Weyrich of The Baltimore Sun reports.
The Orioles outrighted Johnson to Triple-A Norfolk on Wednesday.
The Orioles optioned Johnson to Triple-A Norfolk on Sunday.
The Orioles selected Johnson's contract from Triple-A Norfolk on Saturday, Andy Kostka of TheBaltimoreBanner.com reports.
Johnson signed a minor-league contract with the Orioles on Tuesday, Roch Kubatko of MASNSports.com reports.
The Padres signed Johnson to a minor-league contract Thursday.
Johnson signed a minor-league contract with the Nationals on Friday, Jesse Dougherty of The Washington Post reports.
Johnson (quadriceps) has been activated from Triple-A Columbus' injured list.
Johnson was placed on the 7-day minor-league injured list Saturday.