Electrocaloric effect (ECE) refrigeration stands out as a promising alternative to conventional compression refrigeration owing to its potential for miniaturization, high energy conversion efficiency, cost-effectiveness, and environmental friendliness. However, the practical applications of ECE refrigeration in lead-free ceramics face limitations due to the challenge of achieving a substantial adiabatic temperature change (ΔT) and a wide operating temperature span (Tspan). In this study, we tackle this challenge by introducing rare-earth Sm3+ ions into Ba(Ti0·90Sn0.10)O3 (BTSn) ceramics to enhance their ECE stability. We comprehensively investigate the structural, dielectric, and ECE properties of (Ba1−3x/2Smx) (Ti0·9Sn0.1)O3 (BSmTSn, x = 0−0.03) ceramics. Our findings reveal that the incorporation of Sm3+ ions leads to a reduction in the temperature at which the permittivity reaches its maximum, accompanied by an increased dispersion compared to undoped BTSn ceramics. Particularly noteworthy is the achievement of a ΔT of 0.9 K with a Tspan of 55.5 °C in the x = 0.005 composition. Furthermore, increasing x to 0.01 enables the realization of a wide Tspan of 70 °C, starting from 30 °C. These significant enhancements in the Tspan across all BSmTSn ceramics, facilitated by the introduction of Sm3+ ions, present a promising strategy for optimizing the ECE performance of BaTiO3-based ceramics.