Since silicon nanoparticles have distinctive physiological properties, they can enter plants and influence their metabolic processes. Brassinolide, a novel, eco-friendly plant growth regulator, works by controlling, altering, or enhancement plant growth processes, such as improving leaves and flowers, the elongation of stems, the evolution and maturity of fruit, etc. In order to learn more about the effects of foliar spraying Begonia semperflorens plants with brassinolide and SiNPs at rate of 0, 5, 10, and 15 mg L⁻¹and 0, 1, 3, and 5 mg L⁻¹, respectively, on vegetative and flowering measurements furthermore their chemical composition. The experiments were conducted at the Kafr El-Sheikh University Faculty of Agriculture's research farm in two consecutive years (2019–2020 and 2020–2021). Plant height and its diameter, branches number , both the fresh and dry weights of vegetative parts, and both the fresh and dry weights of roots were the parameters for vegetative growth. and flowering measurements (the weight of the flowers, both fresh and dry, and the number of flowers per plant) as well as chlorophyll (SPAD) and chemical compositions of leaves (N, P, K%)[. The obtained results indicated that, there were significantly increment for all traits  by using both of  Brassinolide and SiNPs compared with control in the both seasons. It was noticed that applying SiNPs at 15 mg L⁻¹ and brassinolide at 3 mg L⁻¹ led to the best values for all traits under study.