[en] Highlights: • A graphene fiber hydroelectric power generator (GF-Pg) is produced. • A 1 mm GF-Pg with a diameter of 80 µm can supply an output of ca. 0.4 V. • The flexible fiber device can be easily integrated into fabric for electronical label. With the fast development of wearable electronics, portable energy generation devices are attracting our considerable attention. Among them, the wearable self-powered system spontaneously harvesting energy from the environment will be much needed. Herein, a high-performance graphene fiber power generator (GF-Pg) is produced based on graphene oxide (GO) fiber. The GF-Pg has highly oriented GO sheets assembled within the fiber, which provide favorable channels for efficient ion transport and thus harvests energy from the moisture. A single fiber generator unit with a length of less than 1 mm and a diameter of 80 µm was able to supply a voltage output of 355 mV in response to the humidity variation, which could be enhanced to 1.3 V by simply increasing the number of device units. Impressively, this moisture-enabled self-powered fiber could be integrated into flexible textiles to realize an information storage/expression based on the breath activated electronic labels of GF-Pg, demonstrating the promising applications in wearable electronics.