Propane dehydrogenation has been a key technology with great industrial promise for meeting the growing global demand for propylene. Although much effort has been devoted to developing ideal catalysts that demonstrate high catalytic activity, selectivity, and durability at the same time, there have been no reports on the achievement of this goal due to a tradeoff between activity and selectivity/stability. Herein, we report that subnanometric Pt–Ge alloy clusters encapsulated in pure silica MFI zeolite break the activity–stability tradeoff in propane dehydrogenation. We also discovered that MnOx could act as an efficient co-catalyst to reach the full potential of Pt–Ge alloy clusters by preventing hydrogen poisoning. The MnOx-PtGe@MFI catalyst exhibited exceptionally high catalytic activity, selectivity, and durability in the absence of co-fed hydrogen at 600°C, exceeding those of other reported catalysts. Mechanistic study revealed that the combination of subnano-downsizing and Ge doping to Pt was the origin of the exceptional performance, and anti-sintering ability provided by the zeolite cage was not a key to the great enhancement of catalyst stability.