The rapid development of the Internet of Things and artificial intelligence has led to an increase in attention focused on distributed power sources such as triboelectric nanogenerators (TENGs), however, enhancing the energy output from TENGs is crucial for their large-scale application. Here, a constant-voltage TENG (CV-TENG) based on a phase-shift design is presented to enhance the energy output via converting a conventional pulse-voltage output into a constant-voltage one and decreasing the crest factor to 1.03. The average power is unexpectedly increased 1.9-fold compared with that of a pulse-voltage TENG (PV-TENG) without a phase-shift design. The energy enhancement is even more than 3-fold under a capacitance load in response to a low-frequency input. Furthermore, the dynamic process of charge transfer under a capacitance load is revealed, which gives a theoretical guide to improving the energy-output efficiency of a TENG toward 100%. This work provides a paradigm shift when it comes to achieving high-efficiency CV-TENGs, and it is of great importance for the acceptance of TENGs as a major form of energy technology.