In the current context, the use of chemical herbicides is facing numerous challenges such as weed resistance, negative impacts on the environment, and human health concerns. The search for effective and sustainable alternative solutions has become more urgent than ever. Plant essential oils have been proven to be a potential solution, not only because of their safety but also due to their ability to inhibit the growth of weeds and various pests. However, the exploration and application of essential oils from new plant species, especially endemic ones like Neolitsea bidoupensis and Neolitsea hongiaoensis, represent a novel and promising direction. This study was conducted to determine the effects of essential oils from two species of Neolitsea, Neolitsea bidoupensis (NBL) and Neolitsea hongiaoensis (NHL), on the growth of mustard greens (Brassica juncea) and barnyard grass (Echinochloa crus-galli). Experiments were carried out using different concentrations of these essential oils to assess their inhibitory effects on both plant species. The results showed that at a concentration of 20 μL/mL, both NBL and NHL essential oils significantly inhibited the growth of the stems and roots of mustard greens and barnyard grass, achieving up to 100% inhibition for both plant parts. This research marks an important initial step in identifying two species of Neolitsea capable of controlling barnyard grass under laboratory conditions. Consequently, it opens up the potential application of Neolitsea essential oils in sustainable weed management, reducing dependence on chemical herbicides while protecting the environment and human health.