By analyzing $4.48times10^8$ $psi(3686)$ events collected with the BESIII detector, we observe the decays $chi_{cJ} to n K^0_SbarLambda + c.c.$ ($J=0$, 1, 2) for the first time, via the radiative transition $psi(3686) to gamma chi_{cJ}$. The branching fractions are determined to be $(6.67 pm 0.26_{rm stat} pm 0.41_{rm syst})times10^{-4}$, $(1.71 pm 0.12_{rm stat} pm 0.12_{rm syst})times10^{-4}$, and $(3.66 pm 0.17_{rm stat} pm 0.23_{rm syst})times10^{-4}$ for $J=0$, 1, and 2, respectively.
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