The 49ers sent a third-round pick and fourth-round selection in the 2020 NFL Draft to the Broncos for Sanders and a fourth-rounder next year, according to the team. The deal is pending a physical.
"Emmanuel is a passionate football player whose toughness and competitive nature have helped him become a dynamic playmaker in this league," 49ers general manager John Lynch said in a statement Tuesday. "He possesses a number of qualities, on and off the field, that we value in our players.
"His familiarity in a similar offensive system will allow for a quick transition. We are excited to add Emmanuel to our roster and look forward to seeing him positively impact our team."
The Pittsburgh Steelers originally selected Sanders in the third round of the 2010 NFL Draft out of SMU. He spent four seasons with the Steelers before signing with the Broncos in the 2014 off-season.
Sanders, 32, has 30 receptions for 367 yards and two touchdowns through seven games this season, his sixth in Denver. The two-time Pro Bowl choice suffered a torn left Achilles tendon last December and also underwent surgery on his right ankle in January, but he made a quick recovery and was a full participant in training camp.
The 49ers' current receiver group has combined for 49 catches and 679 yards in six games. San Francisco's top-producing wideout is Marquise Goodwin, who has 11 receptions for 181 yards this season.
The 49ers will play the Carolina Panthers on Sunday at Levi's Stadium in Santa Clara, Calif.