The 30-year-old scored twice in the second half to prepare the Americans for three World Cup qualifiers in the best possible manner.
The strikes also took Dempsey to 35 international goals, second on the all-time goalscorer list for the USA and fourteen behind Landon Donovan in first place.
The USA went 2-0 up through Jozy Altidore and a comical own goal from German goalkeeper Marc-Andre ter Stegen.
Westermann made it 2-1 before Clint took control. A perfect half volley from an Altidore cross restored the two goal advantage before adding a second five minutes later with a beautiful curled effort into the top corner from the edge of the box.
The Germans setup a grandstand finish with two late goals, but the Americans held on to secure a morale boosting 4-3 victory in front of a crowd of 47359.
"You're going to look back on the career and be proud of what you've done," Dempsey said after the game.
"But at the same time ... your teammates help you. They put you in positions, and they help create chances for you, and you've just got to finish them off."