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Using a data sample of (448.1±2.9)×106 𝜓(3686) decays collected at an 𝑒+𝑒− center-of-mass energy of 3.686 GeV by the BESIII detector at Beijing Electron Positron Collider II, we report an observation of the hindered electromagnetic Dalitz decay 𝜓(3686)→𝑒+𝑒−𝜂𝑐 with a significance of 7.9𝜎. The branching fraction is determined to be ℬ(𝜓(3686)→𝑒+𝑒−𝜂𝑐)=(3.77±0.40stat±0.18syst)×10−5, agreeing well with the prediction of the vector meson dominance model. This is the first measurement of the electromagnetic Dalitz transition between the 𝜓(3686) and the 𝜂𝑐, which provides new insight into the electromagnetic properties of this decay, and offers new opportunities to measure the absolute branching fractions of 𝜂𝑐 decays.