There was not as much goalmouth action in the second period, but Ronny struck the decisive blow as Hertha earned three points which take them above Schalke 04 and into sixth in the table.
Petersen's low 20-yard drive from Hunt's layoff gave the visitors an early lead, which was very short-lived as Hertha were awarded an 18th-minute penalty when Theodor Gebre Selassie fouled Ramos in the box.
The striker picked himself up to net his side's equaliser from the spot, and soon completed Berlin's comeback when he squeezed in a shot from a tight angle following a pass from Per Ciljan Skjelbred.
This time though, it was the hosts who were pegged back, as the same combination that accounted for Bremen's first fashioned their second on 32 minutes, only this time the roles were exchanged.
Hunt drove through the middle of the home defence before playing a one-two with Petersen and curling a shot from just inside the area beyond Hertha keeper Thomas Kraft and into the bottom corner.
The second half picked up where the first left off as Ronny netted his fourth of the campaign, tapping in from Peter Pekarik's parried header after Werder had failed to clear Tolga Cigerci's initial cross.
That proved to be the end of the scoring, although Bremen came close to earning just their second point in five games through Luca Caldirolas, and Hunt's 30-yard free kick, which was tipped onto the post.