Microplastics are plastic particles smaller than 5 mm. These particles now pollute oceans, rivers, and soil worldwide, threatening ecosystems and adding to environmental contamination. This study investigated the acute toxicity of earthworms (Eisenia foetida and Eudrilus eugeniae) from soil contaminated with microplastics, specifically low-density polyethylene with a plastic particle size of ≤ 1 mm, (LDPE, ≤ 1 mm). Earthworms were selected related to their role as essential organisms for soil health and function. Earthworms were exposed to four different concentrations (0%, 0.1%, 0.25%, 0.5%, and 1%) of LDPE, ≤ 1 mm with replicates in artificial soil. Results show that the LC50 values of LDPE, ≤ 1 mm microplastics at 14 days for Eisenia foetida and Eudrilus eugeniae were 5.96% and 3.60%, respectively. The microplastics affected both Eisenia foetida and Eudrilus eugeniae and surface damage was observed at LDPE, ≤ 1 mm concentrations above 0.25% after 14 days of exposure. Greater than 10% mortality was observed at a concentration of 1% in Eisenia foetida, and greater than 10% mortality was observed at concentrations above 0.25% in Eudrilus eugeniae. Additionally, a decrease in earthworm weight was observed with exposure to increasing microplastic concentrations. This study has determined the concentrations of microplastics that impact earthworms and helping to fill a knowledge gap regarding microplastics’ impact on soil ecosystems. This study reveals a toxicity trend related to increasing concentrations of microplastics affecting earthworms. The findings lay a foundation for future research on the long-term impacts on earthworm and soil health as well as broader ecological impacts and potential strategies to reduce plastic pollution in soil.