An entertaining game saw few goalmouth incidents from either side with both goal keepers having a quiet afternoon.
Partick were the more incisive team coming forward in the first half and took the lead on the half hour mark. Derek Fleming played a free-kick short to defender Billy Snowdon, and with no home players closing him down he sent a low 25-yard drive into the left corner.
A David Hagen cross which drifted narrowly over after 17 minutes was the nearest Peterhead came in the first half, but they were the more determined side after the break.
Their efforts were rewarded three minutes into added time, substitute Allan Youngson sending a glorious shot from the left side of the penalty area into the top right corner for a dramatic equaliser.