Objectives: Soil compaction is commonly applied to improve seed-soil contact and regulate soil structure in dryland farming; however, the optimal compaction strength remains unclear for foxtail millet production. This study aimed to determine how varying compaction strengths influence soil physical properties, seedling quality, and yield under different drought levels and planting patterns. Methods: A two-year field experiment was conducted with five compaction levels (CK: 0 g center dot cm-2, T1: 200 g center dot cm-2, T2: 325 g center dot cm-2, T3: 450 g center dot cm-2, and T4: 700 g center dot cm-2) under two drought levels (light drought, LD; moderate drought, MD) and two planting patterns (film-mulched hole-sowing, MH; bare-land drilling, BD). Soil moisture, the Three Soil Phase Index (TSPI), seedling growth parameters, and yield components were measured. Random Forest and structural equation modeling (SEM) were applied to identify key driving factors. Results: Compaction significantly altered soil physical structure and increased soil moisture content, particularly at higher compaction levels (T3-T4), with the maximum increase of 133.69% relative to CK observed in the 0-5 cm soil layer. To achieve an ideal soil three-phase structure (TSPI approximate to 100), T3 compaction strength was sufficient under LD conditions, while higher T4 strength was necessary under MD conditions. Compared with CK, the compaction treatments significantly improved three key seedling parameters: emergence rate, plant height, and primary root length, and these improvements were more pronounced under LD and MH conditions. Under LD-MH, T3 achieved the highest emergence rate (82.78%), which was 77.78% higher than that of CK. The highest grain yield was recorded under MD-MH with T3 in 2023 at 4819.04 kg center dot ha-1 , compared with 2517.20 kg center dot ha-1 in CK; this yield improvement was primarily driven by enhanced spike diameter and grain weight per spike, mediated through compaction-induced changes in soil structure. Conclusion: Overall, moderate compaction optimizes seedling establishment and yield, but the optimal level depends on drought level and planting pattern. A strength of 450 g center dot cm-2 is recommended under LD, while higher compaction may be required under MD. The film-mulched hole-sowing pattern further enhances the yield benefits of appropriate compaction.