Two types of inorganic/organic composite films, SnS/P3HT and SnSe/P3HT, were prepared by combining the inorganic nanomaterials tin sulfide (SnS) nanoribbons or tin selenide (SnSe) nanosheets with the organic polymer 3-hexyl substituted polythiophene (P3HT). Using XRD, SEM, EDS, and Raman characterization techniques, the effect of the content of SnS or SnSe on the conductivity (σ), Seebeck coefficient (S), and power factor (PF) of the composite films was examined. The results indicate that the composite materials are physical mixtures of SnS nanoribbons or SnSe nanosheets and P3HT. Among the various compositions tested, the film containing 4% SnS nanoribbons and P3HT (SnS(4%)/P3HT) exhibits the highest power factor, 3.33 μW/mK2, which is 18.9% higher than that of the pure P3HT film (2.80 μW/mK2). The SnSe nanosheets are poorly dispersed within the SnSe/P3HT composite. Moreover, the degree of aggregation increases with the higher content of SnSe, resulting in a significant decrease in σ and failure to improve PF. So, the SnSe/P3HT composite film has no value for thermoelectric applications. Finally, this article studies the application of SnS/P3HT composite films in flexible thermoelectric devices. The SnS(4%)/P3HT flexible device achieved a maximum output power (Pmax) of 16.7 nW at an external load resistance (Rload) of 1.5 kΩ. After being subjected to 1000 cycles of repeated bending at a 4mm radius, the resistance relative deviation value of the SnS(4%)/P3HT composite film is 23.15%.