Bell pepper is one of the main vegetables produced in the world and are among the most commercialized and consumed in Brazil due to their ease of cultivation in small areas and their high economic value. Given the need for vegetable producers to use lower-quality water for irrigation, it is necessary to study inputs that can mitigate the harmful effects of salinity on plants, such as the biostimulant rutin. A study was therefore carried out to assess whether the application of the biostimulant rutin mitigates the harmful effects of salinity when growing yellow peppers in a protected environment. The experimental design used was randomized blocks in subdivided plots with four replications. The plots consisted of four levels of electrical conductivity of the irrigation water (0.3, 1.5, 3.0, and 4.5 dS m-1), and the subplots were four doses of the biostimulant rutin (0.0, 6.0, 12.0, and 18.0 g L-1) applied via foliar. Growth variables such as plant height and stem diameter, production, fruit quality, leaf water potential, gas exchange, brix level, fruit weight, and shoot dry weight were assessed. The data was submitted to analysis of variance and Tukey test at 5%. The doses of the biostimulant rutin did not mitigate the effects of the salts on the plants, and further tests with higher doses of the biostimulant are needed to verify its efficiency. The salts caused a reduction in plant growth, stem diameter, and the dry weight of the aerial part of the yellow bell pepper plants.