The need for ever-growing communications bandwidths has led to an interest in mode-division-multiplexed communications to increase the information carrying capacity of fiber-optic networks. More recently, mode-division multiplexed chip-scale photonic devices have been investigated as a means towards highly integrated photonic components and systems. To date, however, most chip-scale demonstrations have focused on fixed coupling and routing of individual waveguide modes on a chip. In this work we propose and investigate a new technique to dynamically couple and convert between different propagating waveguide modes via symmetry-breaking optomechanical near-field interactions. Silicon nitride waveguides (tSi3N4=175 nm) with air top cladding are fabricated and enable propagation of weakly-confined modes with substantial evanescent field near the waveguide surface. Suspended silicon nitride (tSiNx=200 nm) micro-electro-mechanical structures (MEMS) interact with the propagating mode’s evanescent field. However, the slight offset of the MEMS perturber with respect to the waveguide’s center axis leads to a symmetry breaking mode perturbation. This perturbation converts even propagating modes (e.g. TE0) to higher-order odd modes (e.g. TE1). We present various experimental techniques for characterizing the mode conversion including direct imaging, mode beating, and FFT spectrogram analysis. Simulation and experimental results demonstrate this new concept of using symmetry-breaking optomechanical near field interactions for mode coupling and conversion towards future mode-division multiplexing on a chip.