<p>Recently, seed powders and seed meals have emerged as promising alternatives for weed control, owing to their rich content of allelochemicals. To assess their effectiveness, we conducted a comprehensive systematic review and meta-analysis of published studies, focusing on active compounds, mechanisms of action on weeds, and efficacy across a wide range of weed species. For the systematic review, 375 articles were screened, and 75 relevant articles were selected for inclusion. The findings indicated that seed meals from Brassicaceae plants were commonly used for weed control. A bibliometric analysis (2000–2025) showed a surge in publications in the recent years. The central theme of these studies was weed control, with Brassicaceae serving as the hub node, reflecting a shift of focus from herbicides. Active compounds such as L-DOPA, glucosinolates, phenolics, and flavonoids were identified as key contributors to the mechanism of weed control. The 19 selected studies included in the meta-analysis demonstrated that plant seeds when applied either as seed powder or seed meals significantly reduced weed biomass with higher number of studies focused on annual weeds. The overall effect size in the meta-analysis was -0.77, with a confidence interval ranging from -1.56 to 0.02. The heterogeneity test (I²) was 71.0%. The studies used in the meta-analysis revealed that the United States (42%) and Egypt (42%) contributed the highest number of studies on seed powder and seed meals. This review highlights the need for further research into the use of various seed powder and seed meals for controlling a broader range of weed species.</p>