Both teams scored four tries but St George Illawarra centre Zac Lomax, who scored a double, kicked four goals compared to a solitary conversion by Warriors fullback Reece Walsh.
Warriors centre Viliami Vailea also scored two tries but the star of the match was Dragons fullback Cody Ramsey, who finished with a try and laid one on for Lomax in his first performance of the season in the No.1 jersey.
The loss was compounded for the Warriors by a foot injury that prevented star prop Addin Fonua-Blake finishing the match and may sideline him for a significant period.