The Seahawks signed Johnson as a free agent during the offseason, but he never played a game for the team.
They placed Johnson on injured reserve the day before their season opener with a groin injury. They cut him from injury reserve last week.
He started every game for the 49ers last season and has played 63 games overall over the last four seasons.
The Browns made Orchard a second-round pick in 2015. They released him in final cuts earlier this month, which was featured in Hard Knocks.
Orchard, 25, appeared in 34 games in his three seasons in Cleveland, posting 65 tackles, five sacks, four pass breakups, two forced fumbles and an interception.