In doing so, they also ended any real hope the Saddlers had of making the play-offs and it was top scorer Rickie Lambert that secured the win.
He scored a glancing header in the 34th minute from a cross by Joe Jacobson.
Walsall pushed forward but Kevin Betsy wasted their best chance with a shot which was way off target.
Rovers always played the neater football and defenders Byron Anthony and Steve Elliott snuffed out the home attack. Only a brilliant save by Walsall keeper Clayton Ince prevented Anthony adding a second with a header, while Craig Disley slammed the rebound wide.
Saddlers skipper Tommy Mooney shot wide and with three minutes left Ince pulled off another good save to deny Lambert.