In this report, copper iron sulfide nanoparticles with various composition were synthesized by a thermolysis based wet chemical method. These inherently sustainable nanoparticles were then fully characterized in terms of composition, structure, and morphology, as well as for suitability as a thermoelectric material. The merits of the material preparation include a straightforward bulk material formation where particles do not require any specialized treatment, such as spark plasma sintering or thermal heating. The Seebeck coefficient of the materials reveals P-type conductivity with a maximum value of 203 µV/K. The results give insight into how to design and create a new class of sustainable nanoparticle material for thermoelectric applications.