The proliferation of online self‐archiving platforms has greatly facilitated the dissemination of new research findings. However, the extent to which these platforms have increased the impact of research remains uncertain, especially considering the potential bias of researchers favoring the deposition of higher‐quality preprints. To determine the causal relationship between self‐archiving platforms and research impact, we conducted an investigation using a sample of 5423 published articles from 2018 that had preprints deposited on bioRxiv. These articles were compared to a control group of 7862 similar articles without preprints, identified through text‐mining algorithms. By modeling the differences in forward citations over time between the two groups, we established a positive causal effect of self‐archiving platforms on research impact. However, the effect observed in this study was smaller than that reported in previous studies (18.7% vs. 36%), indicating a more accurate and unbiased result. Additionally, the study explored the underlying mechanisms that contribute to the enhancement of research impact, including early dissemination and increased exposure through social networks facilitated by self‐archiving platforms. Overall, this study expands our understanding of how research is disseminated in the era of Internet platforms.