We experimentally observe many-body localization (MBL) of interacting fermions in a one-dimensional quasi-random optical lattice. By monitoring the time evolution of a charge density wave (CDW), we identify the MBL transition. For weak disorder, the system thermalizes, erasing initial order, while for stronger disorder, initial order persists, indicating localization. The stationary CDW order and critical disorder strength depend on interaction strength, consistent with numerical simulations. This dependence is linked to the logarithmic growth of entanglement entropy in the MBL phase. The study focuses on a one-dimensional fermionic Aubry-André model with interactions. The system is realized using ultracold fermions in a quasi-random optical lattice. The CDW order is measured via the imbalance between even and odd sites. In the thermalizing case, the imbalance decays to zero, while in the localized case, it remains non-zero, indicating non-ergodic dynamics. The stationary imbalance serves as an order parameter for the MBL phase. The results show that moderate interactions reduce localization compared to the non-interacting case, increasing the critical disorder strength. The system remains localized for all interaction strengths, with the imbalance decreasing up to a certain interaction strength before increasing again. For large interactions, localization is enhanced. The entanglement entropy grows logarithmically in the MBL phase, with the slope reflecting the localization length. The study demonstrates that MBL persists over a wide range of energy densities. The MBL transition is characterized by a sharp boundary between ergodic and non-ergodic phases. The results highlight the importance of interactions in modifying the localization transition and provide insights into the dynamics of many-body systems. The findings open avenues for further investigations into MBL and its implications for quantum dynamics and thermodynamics.We experimentally observe many-body localization (MBL) of interacting fermions in a one-dimensional quasi-random optical lattice. By monitoring the time evolution of a charge density wave (CDW), we identify the MBL transition. For weak disorder, the system thermalizes, erasing initial order, while for stronger disorder, initial order persists, indicating localization. The stationary CDW order and critical disorder strength depend on interaction strength, consistent with numerical simulations. This dependence is linked to the logarithmic growth of entanglement entropy in the MBL phase. The study focuses on a one-dimensional fermionic Aubry-André model with interactions. The system is realized using ultracold fermions in a quasi-random optical lattice. The CDW order is measured via the imbalance between even and odd sites. In the thermalizing case, the imbalance decays to zero, while in the localized case, it remains non-zero, indicating non-ergodic dynamics. The stationary imbalance serves as an order parameter for the MBL phase. The results show that moderate interactions reduce localization compared to the non-interacting case, increasing the critical disorder strength. The system remains localized for all interaction strengths, with the imbalance decreasing up to a certain interaction strength before increasing again. For large interactions, localization is enhanced. The entanglement entropy grows logarithmically in the MBL phase, with the slope reflecting the localization length. The study demonstrates that MBL persists over a wide range of energy densities. The MBL transition is characterized by a sharp boundary between ergodic and non-ergodic phases. The results highlight the importance of interactions in modifying the localization transition and provide insights into the dynamics of many-body systems. The findings open avenues for further investigations into MBL and its implications for quantum dynamics and thermodynamics.