An ultrasonic surgical instrument and method of deflecting an end effector include an acoustic waveguide with a proximal waveguide body portion defining a longitudinal axis, a distal waveguide body portion having an ultrasonic blade distally projecting therefrom, and an articulation body portion extending between the proximal and distal waveguide body portions. The articulation body portion of the acoustic waveguide is configured to flex a first direction to thereby deflect the ultrasonic blade relative to the longitudinal axis and through a first plane. In addition, the articulation body portion of the acoustic waveguide is further configured to flex a second direction to thereby deflect the ultrasonic blade relative to the longitudinal axis and through a second plane. The second direction is different than the first direction such that the second plane is different than the first plane for multiplanar deflection of the ultrasonic blade relative to the longitudinal axis.