The investigation of the end-point trajectory and the nonlinear oscillation of elastic manipulator with offset payload mounted on moving base has been carried out by demonstrating the modal parameters and dynamic responses of a bi-directionally deflected rotating flexible link manipulator. A large deflection model of a flexible rotating manipulator considering both transverse and axial deformation, dynamics of rotating hub, generic payload, and rigid motion of platform has been derived. Initially, modal analysis has been studied to graphically illustrate the eigenfrequencies and corresponding eigenspectrums, while it has been noted that the system possesses distinct and different vibration characteristics as compared to that of a system without offset payload. A smooth sinusoidal input torque has been imparted to the joint to assess the time dependency factors and parameters, which describe its position inaccuracy over time. Finally, the investigation of influence of essential system attributes on the nonlinear behavior and system instabilities under resonance conditions by analyzing the steady-state solutions has been accomplished. The effect of payload parameters such as mass, inertia, and offset, along with the inertia and stiffness of actuator on the frequency response curves has been demonstrated graphically. This work exhibits that the system’s dynamics diversely evolve with a change of offset parameters while system loses its stability due to saddle-node bifurcations. The present result offers specific guidelines towards the design and control aspects of flexible manipulators based on the selection of offset parameters. © IMechE 2020.