The estranged couple were due to appear at four official Twilight conventions hosted by Creation Entertainment, but have cancelled in the wake of Stewart's cheating scandal. Taylor Lautner has also backed out.
"The passion and dedication of Twilight fandom has been amazing and we're out to throw one last giant convention, a final gathering to see old friends that have made up the Twilight family," Creation Entertainment told Zap2it.
"Although Rob, Kristen and Taylor will not be with us this time out we will have a super lineup of other Twilight stars and the weekend will be filled with special events, movie prop and costume displays, contests, panels, auctions, parties, exclusive merchandise, music and much more, including some surprises!"
The conventions are scheduled to be held on the weekends of August 25 (San Antonio), September 29 (Detroit), October 5 (Parsippany, NJ), and November 3 (Los Angeles).
Stewart will reportedly make her next red-carpet appearance at next month's Toronto Film Festival.