Marsh, 26, entered the league as a fourth-round pick in the 2014 NFL Draft out of UCLA by the Seahawks. He played three seasons in Seattle before the franchise traded him to the New England Patriots prior to the beginning of the 2017 season.
The Patriots eventually waived Marsh after nine games and the San Francisco 49ers claimed him. He spent two seasons with the 49ers before the team released him this off-season.
"It's a special place for sure," Marsh said about Seattle. "I personally developed some bonds that will last me the rest of my life. There's a lot of guys I played with here who I stayed in contact with and I really love as brothers, so it means a lot to come back to where I started.
"I love this fanbase and the coaches. There's a lot of positive things about coming back here -- my girl, her parents are from here, it's where she's from. We just had a child, so having that support is huge for us. There's just a lot of positivity around coming back here. I'm pretty pumped."
Marsh appeared in all 16 games with the 49ers last season and recorded 27 tackles and 5.5 sacks, both career highs.
The Cleveland Browns originally selected Orchard in the second round of the 2015 draft. The defensive end/outside linebacker spent his first three seasons with the Browns but failed to make the team's roster before the 2018 season.
Orchard has recorded 69 tackles, 5.0 sacks, five passes defensed, one interception and two forced fumbles in 38 career NFL games.