This paper investigates the influence of geometric cues on the differentiation of human mesenchymal stem cells (MSCs) from bone marrow. The authors demonstrate that cell shape, independent of soluble factors, significantly affects MSC differentiation into osteoblasts or adipocytes. Cells cultured in rectangles with increasing aspect ratios and pentagonal shapes with different subcellular curvatures, all occupying the same area, show distinct adipogenesis and osteogenesis profiles. The results suggest that geometric features that increase actomyosin contractility promote osteogenesis, aligning with in vivo microenvironment characteristics. Cytoskeletal-disrupting pharmacological agents modulate shape-based trends in lineage commitment, confirming the critical role of focal adhesion and myosin-generated contractility during differentiation. Microarray analysis and pathway inhibition studies indicate that contractile cells promote osteogenesis by enhancing c-jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK1/2) activation, along with elevated wingless-type (Wnt) signaling. Overall, the study highlights the significant role of geometric shape cues in orchestrating mechanochemical signals and paracrine/autocrine factors that direct MSCs to appropriate fates.This paper investigates the influence of geometric cues on the differentiation of human mesenchymal stem cells (MSCs) from bone marrow. The authors demonstrate that cell shape, independent of soluble factors, significantly affects MSC differentiation into osteoblasts or adipocytes. Cells cultured in rectangles with increasing aspect ratios and pentagonal shapes with different subcellular curvatures, all occupying the same area, show distinct adipogenesis and osteogenesis profiles. The results suggest that geometric features that increase actomyosin contractility promote osteogenesis, aligning with in vivo microenvironment characteristics. Cytoskeletal-disrupting pharmacological agents modulate shape-based trends in lineage commitment, confirming the critical role of focal adhesion and myosin-generated contractility during differentiation. Microarray analysis and pathway inhibition studies indicate that contractile cells promote osteogenesis by enhancing c-jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK1/2) activation, along with elevated wingless-type (Wnt) signaling. Overall, the study highlights the significant role of geometric shape cues in orchestrating mechanochemical signals and paracrine/autocrine factors that direct MSCs to appropriate fates.