Graphene, a single layer of two-dimensional carbon atoms, has attracted potential attention due to its unique electronic, optical, thermal, and mechanical properties. These features make it highly promising for applications in flexible electronics and energy conversion devices, including touch screens, field effects transistor (FET), capacitors, battery, solar cells, and light emitting diode (LED). Recently our group has raised a wet-spinning method to fabricate neat graphene fibers from concentrated giant graphene oxide (GGO). Although the neat graphene fibers showed moderate electrical conductivities, limited properties of chemically synthesized graphene sheets prevent various applications of graphene fibers, especially flexible electronics. Therefore, to achieve graphene fibers with both high electrical conductivity and excellent mechanical properties, it is inevitable to hybridize conductive silver nanoparticles (AgNPs) to a one-dimensional graphene fiber through the reduction of metal precursors in graphene fibers. Percolation of the silver nanoparticles inside the fibers leads to a outstanding conductivity (~105 Scm-1), which is preserved at high bending deformation. The fiber-type transistor constituted of graphene and AgNPs hybrid fiber as electrodes materials and P3HT channel/ion gel dielectric layers, exhibited the excellent flexibility (bendable and rollable) and transistor characteristics (hole mobility of 18 cm2 V-1s-1, on/off current ratio of 104, and the threshold voltage of 2.3 V).