This work deals with the effects of long‐term storage on the properties of polyamide 12 filled with nanoclay mass fractions of 0, 3, and 5%. More precisely, such nanocomposites were prepared using internal mixer, and then stored in a room under ambient conditions, for 6 years, protected from light and temperature variations. The changes in their thermal, mechanical, and rheological properties were analyzed, in relationship with the microstructure changes. Various analyses and tests were conducted, including wide‐angle X‐ray diffraction experiments, water mass loss evaluation, differential thermal analyses, strain sweep tests on solid‐state specimens, as well as time sweep and oscillatory shear measurements on melt‐state specimens. The results mainly revealed the effects of the absorbed water on the changes of the aged nanocomposite performances and highlighted the positive role of nanoclay platelets in the preservation of processability and end‐use properties.