Flexible thermoelectric (TE) devices for maintenance-free and long-lasting power source that makes use of the body heat, industrial waste heat and even solar heat have been of growing interest. Low-dimensional nanomaterials, such as 2D TMDCs (transition metal dichalcogenides) and 1D CNTs (carbon nanotubes), are the best-known candidate materials for high-performance flexible TE devices. TiS₂/organics hybrid superlattice materials and CNTs-based nanocomposites will be focused and their interesting structures, TE properties, and manufacturing processes are demonstrated and discussed. Some examples of device applications of the low-D nanomaterials are also presented.