A hinge assembly includes a first pivot shaft, a second pivot shaft, a third pivot shaft, a first bracket, a second bracket, a first meshing wheel, a second meshing wheel, a third meshing wheel, and a transmission belt member sleeved on both the first meshing wheel and the third meshing wheel. The first pivot shaft, the second pivot shaft, and the third pivot shaft are substantially parallel. The first and second brackets are non-rotatably sleeved on the first and second pivot shafts, respectively. The third meshing wheel is disposed between the first meshing wheel and the second meshing wheel, and meshes with the second meshing wheel and the transmission belt member. An electronic device using the hinge assembly is also provided.