Bell has not been with the team during the preseason, working out on his own during his holdout.
On Tuesday, a fan tweeted to James, "So like when is le'veon bell gonna show up??," @Vadarmendariz asked in regard to fantasy football.
Bell tweeted a simple response: "9-1-17" with a wink emoji. When the fan responded that his announcement was good news, he replied, "you're welcome."
Sept. 1 is one day after the Steelers' preseason finale against the Cleveland Browns.
Last season, Bell totaled 1,884 yards from scrimmage and nine touchdowns in just 12 games because of suspensions and injuries.
Bell, 25, was designated by the Steelers as their franchise player for 2017. Because the deadline passed for teams and franchise players to sign a long-term contract, Bell is restricted to a one-year, $12.1 million deal for 2017.
The Steelers can tag the Bell for the second straight season in 2018 at $14.54 million or re-sign him. The franchise tag still leaves Bell as the league's highest-paid tailback in 2017.
Bell, who is recovering from groin surgery, aggravated the injury that kept him on the sideline for the majority of last season's AFC Championship Game against the New England Patriots.
The Steelers rode Bell to the playoffs in 2016. He rushed for 1,268 yards and seven touchdowns and caught 75 passes for another 616 yards and two scores during the regular season, becoming the first player in NFL history to average 100 rushing yards and 50 receiving yards per game.