Intensive chemical pesticide usage in crop protection for pest control causes major pollution of the environment. Replacing chemical pesticides with biopesticide is an essential agro-ecological principle that should be considered in agro-ecosystems. In this study, a novel biopesticide formulation based on plant extract was prepared, and then aphid’s mortality in cucumber greenhouses was evaluated in comparison to common chemical insecticide. Our eco-friendly insecticide consists of methanolic extract of Rosmarinus officinalis (4.38 gr in 1 lit water) and succinic acid (0.5 gr in 1 lit water) in combination with Triton^® X-100 (10 ml in 1 lit water), canola seeds oil (10 ml in 1 lit water), and potassium nitrate (5 gr in 1 lit water). Also, the common insecticide against Aphis gossypii in cucumber greenhouses is dichlorvos (Dichlorvos^® 48% EC) which was applied at the recommended dose (0.6 gr a.i./lit). 24 h after sprayings, survived aphids on each treatment were recorded, and mortality percentages were calculated. Results showed that in biopesticide treatment, mortality (65.6 ± 2.8 %) have no significant difference compared to dichlorvos (71.1 ± 2.9 %) (P = 0.0629). Finally, plant performance including numbers of leaves (P = 0.0951), flowers (P = 0.0842), fruits (P = 0.0730), and branches (P = 0.0698) were not influenced by the biopesticide application. Our results propose that the mentioned biopesticide can be used in cucumber greenhouses for aphids control with no adverse effect on plant growth and development, leading to zero-pollution tactics in crop protection which are necessary for sustainable agriculture.