<p>Mg-Al-Si alloys are designed for creep resistance, but high Si and Al contents lead to coarse Mg₂Si phases and brittle eutectic structures, compromising mechanical performance at elevated temperatures. While research often targets alloys with Si ≥ 1.0 wt.%, low-Si, low-Al alloys with Sn additions are critical for enhancing mechanical properties. This study examines the microstructure, compressive strength, and creep behavior of a Mg-3.0Al-0.5Si alloy modified with 1.0 and 2.0 wt.% Sn, produced via stir casting, and compares its performance to a Mg-2.0Al-0.5Si-2.0Sn alloy to assess the influence of Al content. The addition of Sn significantly refined grain size and altered precipitate morphology, reducing the size and volume of Mg₁₇Al₁₂ and Mg₂Si phases, while Mg₂Si phases adopted smaller polyhedral forms. Mg-3.0Al-0.5Si-xSn alloys display improved microhardness, compressive yield strength (CYS), ultimate compressive strength (UCS), total strain to fracture (TSF), and work of fracture (WOF) at 298 and 473&#xa0;K. Among the alloys, the Mg-2.0Al-0.5Si-2.0Sn alloy has the highest microhardness, CYS, UCS, TSF, WOF, and strain hardening response in the operating temperatures. The impression creep resistance of Mg-3.0Al-0.5Si alloy considerably improved following Sn addition and further proliferated with the reduction of Al content in Mg-2.0Al-0.5Si-2.0Sn alloy. The creep response was mostly governed by pipe diffusion-driven dislocation creep. The Mg-2.0Al-0.5Si-2.0Sn presented the maximum strength and creep resistance, while the Mg-3.0Al-0.5Si-2.0Sn alloy demonstrated best ductility and optimum strength and creep resistance.</p>