<p>Cryogenic magnetocaloric materials (MCMs) attract growing attention for solid-state refrigeration technologies, especially in sub-Kelvin applications such as quantum computing and space exploration. Among various candidates, rare-earth-based compounds containing Gd³⁺ and Eu²⁺ ions exhibit remarkable magnetocaloric effects due to their large spin (<i>J</i> = <i>S</i> = 7/2 and <i>L</i> = 0), weak magnetic anisotropy, and tunable magnetic interactions. This review summarizes recent progress on the structure–property-performance of representative Gd³⁺/Eu²⁺-based compounds, including fluorides, phosphates, hydroxides, halides, and metal–organic frameworks. Key design principles are proposed for optimizing cryogenic MCMs, including high magnetic ion concentration, weak or single-ion magnetic coupling, and suppressed magnetic ordering. Finally, we also discuss spin supersolid materials Na₂BaCo(PO₄)₂, which exhibits excellent adiabatic demagnetization cooling temperature below 100 mK, and look into the future of cryogenic magnetocaloric materials and the emerging quantum magnetic phenomena.</p> Graphical abstract <p></p>