Curly Parsley (Petroselinum crispum) seeds were planted for the purpose of essential oil extraction from dried plants by hydro-distillation. GC-MS analysis of parsley essential oil (PEO) showed that Parsley-apiol (40.42%) and myristicin (34.77%) were the major components. PEO and its nanoemulsion (PEO-NE) were tested for their antifungal activities against Alternaria solani, the causal agent of tomato early blight, and Rhizoctonia solani, the causal agent of faba bean root rot. Isolated fungi were verified by ITS1and ITS4 primers. Their partial region was deposited in the GenBank (NCBI) under OL305707 and OL305708 accession numbers for A. solani and R. solani, respectively. In vitro treatments with PEO and PEO-NE showed a significant difference in the growth of both fungi under study when compared with their negative and positive controls. PEO highest effect was recorded at 3000 mg/L while PEO-NE was recorded at 1500mg/L without significant difference from the commercial fungicide (positive control). Pathogenicity test was confirmed by evaluating the antifungal activity by detached leaf assay on tomato and radical assay on faba bean for A. solani and R. solani, respectively. This study reflects the possibility of replacing harmful fungicides with natural products, such as PEO and its nanoemulsion, against A. solani and R. solani. Eco-friendly products, e.g., natural extracts, are a must now, to be used to decrease the negative impact towards general health and pollution from using commercial chemicals.