The North's official KCNA said "revelation showed" Park had masterminded a plot to execute its "supreme leadership" in 2015 and it was imposing the "death penalty on traitor Park Geun-hye."
KCNA did not disclose the source of the revelation but a Japanese newspaper reported this week that Park in 2015 approved a plan to overturn the North Korean regime of leader Kim Jong Un.
Park was ousted in March over a corruption scandal and is in detention while on trial.