Nick Hundley responded in the next half-inning by belting a lead-off triple off Edward Mujica (8-5) that just missed going out for a homer.
After the Marlins intentionally walked the bases full, Mike Dunn entered and surrendered a game-winning hit to Venable.
The San Diego right fielder also smacked a first-inning homer and Kevin Blanks followed with a two-run double as the Padres finished with 7-0 record against the Marlins this season.
Mike Stanton also homered for Florida.
Former Titans kicker dies in car crash
UPI Sports Results for September 20, 2014