Mature fine tailings (MFT) are one of the major environmental problems associated with the oil sands industry in Canada. To help mitigate the negative impact tailings have on the environment, we prepared MFT/starch composites and studied their morphology, water resistance, and mechanical properties as a function of filler percentage. The motivation behind this approach is to turn waste tailings into a source of potentially useful materials. We compared the MFT/starch composites to similar composites made with montmorillonite (MMT), cellulose nanocrystals (CNC), and Dean Stark solids (DS). The water resistance of MFT/starch and DS/starch composites improved 6% at the highest filler content. MFT/starch and DS/starch composites had similar mechanical properties, but performed better than plasticized starch, with an increasing tensile modulus with increasing filler content. Despite the higher modulus increase in intercalated MMT/starch and CNC/starch composites (up to 5% filler), the MFT/starch composites with filler contents higher than 10% achieved the same tensile modulus values; since our objective was to transform as much MFT as possible into useable materials, this can be seen as a positive feature of these composites. The dynamic mechanical analysis of the composites showed they were heterogeneous and identified a plasticizer-rich phase and a starch-rich phase.