Wallace was at the team facility Tuesday morning. A restricted free agent, he had yet to sign his one-year contract tender worth approximately $2.7 million.
He also will undergo routine medical exams, but will not practice with his teammates until next week.
Last season, Wallace had 72 receptions for 1,193 yards and eight touchdowns. He has 24 receiving touchdowns in his three-season career.
Wallace led the NFL in yards per catch (19.4) as a rookie third-round pick out of Mississippi in 2009. Wallace ranked second in the league (21.0) the following season, when he had a career-high 1,257 yards.
"We definitely understand the business part of things, and we don't worry about that too much," receiver Emmanuel Sanders said. "But as far as in the offensive room, we've missed his personality and we've missed what he brings to the table.
"Everyone's excited that he's back."
Wallace did not receive any offers from other teams as a restricted free agent this spring. Any team signing him to an offer sheet would have had to provide compensation to the Steelers.
Via agent Bus Cook, Wallace and the Steelers were negotiating his preferred long-term extension. But the club vowed not to negotiate once training camp began if he did not report, so there has been no contact between the sides since July 25.
The Steelers' long-standing policy is not to negotiate contracts during the regular season, giving the two sides less than two weeks to iron something out.
Wallace was given a playbook and was said to be studying up on new offensive coordinator Todd Haley's offense. He also has been working out with a trainer in Florida.