Hundley's RBI double in the first inning gave the Padres a 1-0 lead and his run-scoring triple in the third handed San Diego a 3-1 advantage.
The Padres catcher then capped his big day with a two-run shot in the fifth and San Diego closed out the victory, evening its four-game series against the Phillies.
Anthony Bass (1-2) turned in a strong start, allowing only one unearned run on three hits over six innings, surviving five walks while striking out seven.
Joe Blanton (1-3) was roughed up for six runs (three earned) on seven hits in a six-inning effort for the Phils.
Juan Pierre went 3-for-4 for Philadelphia, which lost for the fourth time in six games.