The thermoelectric (TE) materials and corresponding TE devices can achieve direct heat-to-electricity conversion, thus have wide applications in heat energy harvesting (power generator), wearable electronics and local cooling. In recent years, aerogel-based TE materials have received considerable attention and have made remarkable progress because of their unique structural, electrical and thermal properties. In this review, the recent progress in both organic, inorganic, and composite/hybrid TE aerogels is systematically summarized, including the main constituents, preparation method, TE performance, as well as factors affecting the TE performance and the corresponding mechanism. Moreover, two typical aerogel-based TE devices/generators are compared and analyzed in terms of assembly modes and output performance. Finally, the present challenges and some tentative suggestions for future research prospects are provided in conclusion.