An open-irrigated ablation catheter system includes a catheter body, and an electrode tip body mounted on a distal portion of the catheter body. The electrode tip body includes a proximal end configured for connection to the catheter body and a wall defining an open interior region and including one or more irrigation ports. The wall is conductive for delivering radio frequency (RF) energy. The catheter system further includes a proximal insert positioned partially within the catheter body and at least partially within the proximal end of the electrode tip body. The proximal insert includes a fluid inlet for receiving a cooling fluid delivered via the catheter body. The proximal insert forms a flow path configured to direct the cooling fluid from the fluid inlet to cool the distal portion of the catheter body and to cool a junction of the catheter body and the electrode tip body.