A stochastic optimal coupling-control method for adjacent building structures is proposed. The coupled structures with control devices under random seismic excitation are condensed to form a reduced-order model for the control analysis. The stochastic averaging method is applied to the reduced model to obtain ItΓ΄ o stochastic differential equations with respect to structural modal vibration energies. Then the stochastic dynamical programming principle is applied to the energy processes to establish a dynamical programming equation, by which the optimal coupling-control law is determined. The seismic response mitigation is achieved through the structural energy control and the dimension of optimal control problem is reduced. The seismic excitation spectrum is taken into account according to the stochastic dynamical programming principle. The random response of the non-linear controlled structures is predicted by using the stochastic averaging method and is compared with that of the uncontrolled structures to evaluate the control efficacy. A numerical study is conducted to demonstrate the response reduction capacity of the proposed stochastic optimal coupling-control method for adjacent building structures.