Biobased poly(L-lactide) (PLLA) undoubtly represents an interesting alternative to petro-based polymers but still remains excluded from most of high-value and durable applications. The introduction of poly(methyl methacrylate) (PMMA) in poly(lactides)-based materials is thereby exposed to develop polymer blends with new functionalities and superior thermomechanical properties. The miscibility between PLLA and PMMA was first evaluated and only miscible blends were recovered using melt-processes. Interestingly, these miscible binary blends are marked by a high transparency with tunable, enhanced and promising thermomechanical and barrier performances. PMMA was also found to be miscible with stereocomplexable poly(lactides) and, surprisingly, the amount of PLA stereocomplexes formed during high-speed cooling is significantly enhanced by PMMA. Consequently, highly-crystalline ternary PLLA / PDLA / PMMA blends can be easily produced with impressive and complex thermomechanical behaviour. Shape-memory effects in miscible PLLA / PMMA blends were also investigated and triple-shape memory effects were demonstrated. Broad relaxation time distributions coupled to appropriate stretching conditions mainly drive the recovery of multiple shapes and the symmetric formulation was found to be particularly suitable for these advanced applications. In this respect, multiple-shape memory materials based on poly(lactides) could be efficiently and easily designed with miscible blends processed by melt-blending approaches. Obviously, the use of PMMA into poly(lactides)-based materials affords high-performances materials with outstanding and fascinating properties. The association of PMMA to poly(lactides) could consequently play a key role for the introduction of biobased poly(lactides) into technical, durable and smart applications.