Nanoscale piezoelectric energy-harvesting from ambient vibration sources has great potential for practical applications in powering nanoelectronic and nano-wireless sensors. Nowadays, the piezoelectric laminated sandwich smart nanocomposites have been extensively applied as nanogenerators, nano-energy harvesters, and the other nano-electromechanical devices. However, no works have thoroughly investigated the size-dependent dynamic thermo-electromechanical response of such structure that consider the perfect/non-idealized interfacial conditions and piezoelectric material constants ratios. This article will address this problem based on the size-dependent piezoelectric thermoelasticity theory by a semi-analytical technique via the Laplace transformation. If the thermal/elastic nonlocal parameters or material constants ratios are properly selected, the results show that: (a) the electrical energy harvesting and heat isolation can be maximally improved; (b) the harmful thermal stresses will be lowered to some extent. This work not only provides a thorough and comprehensive understanding on response of piezoelectric laminated sandwich smart nanocomposites serving in non-uniform thermal environment, but also offers basic guidelines for its thermal management and piezoelectric energy harvesting.