A supporting mechanism and a related electronic device can be adapted to apply to rotation of a signal transmission holder. The rotary supporting mechanism includes a base, a bracket, a first connecting rod, a second connecting rod, a third connecting rod and a actuating component. The signal transmission holder is disposed on the bracket . Two end of the first connecting rod respectively pivot between the base and the bracket. A first end of the second connecting rod pivots to the bracket . Two ends of the third connecting rod respectively pivot to the base and a second end of the second connecting rod. The actuating component is rotatably disposed on the second connecting rod. A contacting portion of the actuating component is movably shifted between a first blocker and a second blocker of the third connecting rod since the second connecting rod rotates relative to the third connecting rod.