Lisianthus is a major cut flower, but it has a short vase life. To prolong postharvest longevity and improve quantitative and qualitative traits of cut lisianthus flowers, an experiment was conducted on the basis of a Completely Randomized Design with eight treatments on 120 flower sprays in three replications. The experimental treatments included salicylic acid (SA) at the rates of 50, 100 and 200 mg L-1, cerium nitrate [Ce(NO3)3] at the rates of 20, 40, 80, and 200 μM, and control (distilled water). The results revealed that the flowers treated with 40 μM Ce(NO3)3 and those treated with 100 mg L-1 SA had the longest vase life of 15.42 and 15.20 days, respectively. Also, these treatments were most effective in improving water uptake, reducing microbial load at the stem end, and enhancing petals’ protein content. The lowest malondialdehyde (18.65 nmol g-1fresh weight) was related to the treatment of 40 μM Ce(NO3)3 and 100 mg L-1 SA. These treatments showed the lowest polyphenol oxidase (PPO) activity, too. The activity of ascorbate peroxidase (APX) and peroxidase (POD) antioxidant enzymes was significantly higher in the flowers treated with 40 μM Ce(NO3)3 and 100 mg L-1 SA. The treatment of 200 mg L-1 SA had negative effects on all the recorded traits. So, it can be concluded that the treatment of cut lisianthus flowers with 40 μM Ce(NO3)3 and 100 mg L-1 SA can prolong their postharvest longevity by reducing lipid peroxidation and increasing the activity of antioxidant enzymes.