The Dax climbed past the 25,900-point mark for the first time in its history on Monday, erasing the previous record set in early July.
The German benchmark index gained 1.5% in the session, reflecting a broadening of buying interest across European equities as geopolitical risk premiums unwound.
The rally was fueled by growing market confidence that the military confrontation between the United States and Iran is de-escalating.
Investors appear to be pricing in a potential diplomatic resolution, following recent signals from US President Donald Trump that a settlement is within reach.
This shift in sentiment has provided a significant tailwind for risk assets, allowing the Dax to break through its previous ceiling with relative ease.
The move marks a continuation of the index's recent upward trajectory, which had been constrained by fears of a prolonged conflict disrupting global energy supplies and trade routes.