A mass timber lateral force resisting system (LFRS) is proposed using a timber buckling restrained brace (TBRB) for improved seismic performance in high seismic applications. To develop a high-performance braced frame, it is essential to quantify the behaviour of the connections including failure modes and moment-rotation capacities. Cyclic and monotonic tests were conducted on six mass timber beam-column connections to investigate the response of mass timber joints connected with slotted-in steel plates and mild steel dowels. The goal of the subassembly tests was to measure the maximum rotation of such connections for monotonic and cyclic loads; these results were used to optimize the number of mild steel dowels for the TBRB frame design. The tests showed that the connections with three different steel dowel details reached a maximum rotation of 0.11 rad. with no loss of strength. Scaled tests of a full braced timber frame with a TBRB were carried out to verify the LFRS which included the effect of column axial load and out-of-plane displacements.