Rodriguez tapped out former Cage Rage British heavyweight champ Rob Broughton with a kneebar in the second round.
According to the Liverpool Echo, Broughton was winning on points in round one, landing more strikes in clinch and avoiding all of Rodriguez's takedown attempts. However, Rodriguez needed only once successful takedown to allow him to move into dominant position for the submission.
Rodriguez (32-9-1) has now won four straight since losing on pay-per-view to Travis Wiuff in the semifinals of YAMMA's single-night heavyweight tournament on April 11.
In September 2002, Rodriguez defeated Randy Couture to win the UFC heavyweight title but dropped the belt in his next fight to Tim Sylvia.
Cage Gladiators 9 was taped for broadcast on ITV 4, UK's version of Spike TV.