Ferroelectric tunnel junctions (FTJs) are promising for high-reliability, low-power non-volatile memories and computing devices. However, maintaining high tunneling electroresistance (TER) in atomic-scale ferroelectric layers is challenging due to structural instability and large depolarization fields. This study reports on FTJs based on samarium-substituted layered bismuth oxide (Sm-Bi2-xSmyO3), which can maintain a TER of \(7 \times 10^5\) with a 1-nanometer Sm-Bi2-xSmyO3 film, three orders of magnitude higher than previous reports. The high TER is attributed to efficient barrier modulation by the large ferroelectric polarization. These FTJs demonstrate up to 32 resistance states, high endurance (over \(5 \times 10^9\)), high linearity of conductance modulation, and long retention time (10 years). The TER over \(10^6\) is achieved in FTJs with a 4.6-nanometer Sm-Bi2-xSmyO3 layer, surpassing commercial flash memories. The results show significant potential for multi-level and reliable non-volatile memories. The study also explores multi-level cells and analog memory properties, achieving 32 distinct resistance states and linear conductance modulation. The devices exhibit high endurance, long retention, and small device-to-device variation, making them highly promising for low-power, high-reliability, and high-density non-volatile memories and in-memory computing.Ferroelectric tunnel junctions (FTJs) are promising for high-reliability, low-power non-volatile memories and computing devices. However, maintaining high tunneling electroresistance (TER) in atomic-scale ferroelectric layers is challenging due to structural instability and large depolarization fields. This study reports on FTJs based on samarium-substituted layered bismuth oxide (Sm-Bi2-xSmyO3), which can maintain a TER of \(7 \times 10^5\) with a 1-nanometer Sm-Bi2-xSmyO3 film, three orders of magnitude higher than previous reports. The high TER is attributed to efficient barrier modulation by the large ferroelectric polarization. These FTJs demonstrate up to 32 resistance states, high endurance (over \(5 \times 10^9\)), high linearity of conductance modulation, and long retention time (10 years). The TER over \(10^6\) is achieved in FTJs with a 4.6-nanometer Sm-Bi2-xSmyO3 layer, surpassing commercial flash memories. The results show significant potential for multi-level and reliable non-volatile memories. The study also explores multi-level cells and analog memory properties, achieving 32 distinct resistance states and linear conductance modulation. The devices exhibit high endurance, long retention, and small device-to-device variation, making them highly promising for low-power, high-reliability, and high-density non-volatile memories and in-memory computing.