Stability and mechanical reliability are becoming 'bottleneck' challenges in perovskite solar cells (PSCs), a burgeoning photovoltaic (PV) technology. This is because the low formation-energies of metal-halide perovskite (MHP) light absorbers at the heart of PSCs that makes them easy to solution-process renders them inherently poor in stability and mechanical properties: they are compliant (low Young’s modulus), soft (low hardness), and brittle (low toughness). To address these final technical hurdle in the path towards PSCs commercialization, several rationally designed microstructural and interfacial tailoring approaches are used. These include grain-coarsening, grain-boundary functionalization, and interfacial engineering. Most importantly, these approaches are designed such that they not only enhance the PSCs mechanical reliability but also increase power-conversion efficiency and improve stability. The scientific rationales for these approaches are discussed, together with the presentation of the current results.