A selective catalytic reduction (SCR) system includes a SCR canister including a SCR inlet configured for receiving engine exhaust from a work vehicle and a SCR outlet configured for expelling a treated exhaust flow. The system includes first and second SCR chambers housed within the SCR canister and configured to react mixtures of exhaust reductant and associated first and second portions of the engine exhaust with a catalyst to generate first and second treated exhaust flow portions, respectively. The system includes an outlet chamber positioned between the SCR outlet and the first and second SCR chambers. Moreover, the outlet chamber is configured to combine the first and second treated exhaust flow portions to form the treated exhaust flow. Further, the system includes a chamber mixer positioned upstream of the SCR outlet and configured to promote mixing of the first and second treated exhaust flow portions within the outlet chamber.