Nicks, 31, was one of more than 100 players who attended an XFL Summer Showcase in Montclair, N.J. The former Super Bowl champion has not played in the NFL since a second stint with the Giants in 2015.
The XFL is holding showcases around the country in preparation for its relaunch in February 2020. The original XFL's only season was in 2001.
Running back Branden Oliver, receiver/running back Dexter McCluster and former Green Bay Packers quarterback Joe Callahan were among the other players who participated in the showcase.
Nicks was a first-round pick of the Giants in 2009. He had 318 receptions for 4,676 yards and 27 touchdowns with the Giants from 2009 to 2013.
Nicks registered 38 catches and four touchdowns with the Colts in 2014. He returned to New York for the 2015 season but had only seven catches in six games.