"He's a guy whose arrow is point up," offensive coordinator John Shoop said of Gilmore.
To make room for Gilmore the Bears waived return specialist Vinny Sutherland.
Gilmore has been a member of the Bears practice squad since Sept. 3 after spending training camp and the preseason with the Saints. The 6-3, 265 pounder out of Penn State was chosen by New Orleans in the sixth round (196th overall) of the 2002 NFL draft.
Sutherland was signed Oct. 3 and returned three kickoffs for 49 yards with a long return of 18 yards against Detroit in his only action for the Bears.
Lyman, who came into his third year with just one reception, has made catches and will likely receive his first start since his rookie year.
"He has a great opportunity to be out on the field and make some plays for us and we're sure counting on him," Shoop said. "I don't know if I would ever say this make-it-or-break-it for him, but he certainly has an opportunity to show his value to our team and throughout the league."