This paper performs a numerical proof of concept study to enhance transonic supercritical airfoil cruise performance using Co-Flow Jet(CFJ) active flow control technique. The Reynolds averaged Navier-Stokes(RANS) equations with one-equation Spalart-Allmaras turbulence model is used. A 5th order weighted essentially non-oscillatory(WENO) scheme with a low diffusion Riemann solver is utilized to evaluate the inviscid fluxes. A 4th order central differencing scheme matching the stencil width of the WENO scheme is employed for the viscous terms. Numerical trade studies are carried out to investigate the CFJ geometric effects on the performance enhancement. This research discovers that CFJ can significantly enhance the aerodynamic performance of RAE2822 transonic supercritical airfoil for both lift coefficient CL and aerodynamic efficiency (L/D)c, that includes the CFJ pumping power. For the free-stream condition of M∞=0.729, Re∞=6.5 × 106, and AoA from 0° to 5.5°, the CFJ RAE2822 airfoil is able to achieve a performance enhancement with both CL and (L/D)c, increased simultaneously by 18.7% and 14.5%, respectively at the peak aerodynamic efficiency point. At the maximum lift coefficient point, the CFJ airfoil is able to increase the CL from 0.93 to 1.16 by 25.6% while slight decreasing the (L/D)c, from 21.3 to 19.6. Rigorous mesh refinement study is conducted to ensure solution convergence of the numerical results. Since the baseline airfoil drag is over-predicted by more than 30% due to the inadequacy of the RANS model, the predicted improvement of the CFJ airfoil tends to be on the conservative side. The unique feature of CFJ airfoil to augment lift and reduce drag at low energy expenditure is shown to be able to drastically improve the transonic airfoil cruise performance when the flow is benign at low AoA. The performance enhancement of CFJ transonic airfoil needs to be further proved by wind tunnel experiment as the next step. It is hoped that this research will open a door to significantly enhance transonic airfoil performance since the supercritical airfoil was invented in 1960’s.