van der Waals (vdW)-layered direct bandgap semiconductor materials such as lead iodide (PbI 2 ) possess highly anisotropic optoelectronic properties that are dependent on their layer stacking orientations. Here, we report an in situ control of PbI 2 layer growth orientation, or stacking axis, via the vapor− liquid−solid (VLS) growth. The PbI 2 vdW nanowires initially grow with transverse stacking relative to the [0001]-oriented growing axis, and the controlled introduction of PbBr 2 induces threedimensional twin formation, which is responsible for the change in the layer stacking axis (i.e., kinking). By varying the duration of the PbBr 2 introduction, two different types of kinking modes are confirmed: Type I kink in parallel with the twin boundary (TB) propagation accompanying two mirrored stacking c-axes and Type II kink, in which the layers are stacked parallel to the growing segment. Optoelectronic analyses using photoluminescence and cathodoluminescence reveal that the kinked PbI 2 nanostructures exhibit asymmetric band-edge excitonic emission profiles, which are distinct from those of the single-oriented nanowires. These results demonstrate a new methodology to modulate the structuredependent optoelectronic/photonic properties, as well as phonon transport, which cannot be achieved using conventional 2D design platforms for the vdW-layered materials.