To recycle byproduct waste heat, a new hybrid system model that integrates alkaline fuel cell (AFC) with temperature-matching elastocaloric cooler (ECC) is proposed. Considering diverse irreversible effects in thermodynamic and electrochemical processes, the mathematical model of hybrid system is formulated, and the performance metrics of the hybrid system are obtained. The optimally operating current density range of AFC enabling ECC to work is determined. Numerical calculation shows that the equivalent peak output power density and its according efficiency can be 51.64% and 20.88% higher than that of the single AFC, respectively. ECC is demonstrated to be an effective and competitive technology for AFC waste heat harvesting. In addition, considerable sensitivity analyses are performed to check the dependence of the proposed system performance on some key variables, including operating pressure, operating temperature, thermodynamic loss composite parameter, elastocaloric material types and elastocaloric properties, cross-sectional area ratio and length ratio for ECC. The results derived may offer some insights into the design or operation of practical AFC-ECC hybrid systems.