This paper investigates a wireless?powered relay network, in which a source transmits its signal to a destination with the aid of a decode?and?forward (DF) relay. Contrary to conventional DF relay networks, we consider the scenario that the DF relay has no sufficient embedded energy supply, and it is equipped with an energy harvesting unit and rechargeable battery. As such, it can accumulate the energy harvested from the source’s signals before help forwarding the information. A harvest—transmit—store (HTS) model with in?block time switching (TS) is developed such that TS can be implemented within one transmission block. By modeling the finite?capacity battery of the relay as a finite?state Markov Chain with a two?stage state transition, we derive the closed?form expression for the outage probability of the proposed HTS model with in?block TS over Nakagami?m fading channels. Numerical results validate our theoretical analysis and show that the proposed HTS model with in?block TS significantly outperforms the HTS model without in?block TS in terms of outage probability and successful rate.