<p>Yttrium iron garnet (YIG) ferrites are essential functional materials in microwave technology. A central challenge lies in precisely controlling their electromagnetic characteristics through multi-element doping. In this study, we successfully synthesized novel five-element co-doped YIG ceramics with a nominal composition of Y_2.3Bi_0.7Li_xV_xFe_4.8-2xCu_0.1Sn_0.1O₁₂ (<i>x</i> = 0.005, 0.010, 0.015, 0.020) using a conventional solid-state reaction. Through comprehensive structural analyses, we verified that all dopants were homogeneously integrated (Li⁺, V⁵⁺, Bi³⁺, Sn⁴⁺, Cu²⁺) into the YIG lattice without forming secondary phases, resulting in a consistent lattice expansion as <i>x</i> increased. The saturation magnetization showed minimal variation with doping level, remaining within 22.8 to 24.3&#xa0;emu/g. Notably, the FMR linewidth remained narrow across all compositions and reached a minimum of 179 Oe at <i>x</i> = 0.015, confirming that multi-element co-doping not only preserves but actually improves the microwave magnetic quality of the material. Most notably, the dielectric constant (<i>ε′</i>) was significantly enhanced, peaking at 62.11 at 1&#xa0;MHz for the <i>x</i> = 0.015 composition, while the dielectric loss (<i>ε″</i>) remained low. This performance marks a substantial advancement over earlier YIG-based systems. The optimal <i>x</i> = 0.015 composition exhibits a superior blend of high dielectric constant, low loss, stable magnetization, and a narrow FMR linewidth. Our findings establish the Li-V-Bi-Sn-Cu multi-element co-doping strategy as a highly effective approach for simultaneously boosting dielectric performance and maintaining outstanding microwave magnetic properties in YIG ferrites, positioning them as excellent candidates for advanced high-frequency microwave components like miniaturized filters, phase shifters, and antennas.</p>