This research was conducted at Sylhet Agricultural University to evaluate the effects of different foliar boron application methods on growth, yield and phytochemical composition of Tori-7 (Brassica campestris). Three treatments each having four replications were evaluated: T1, no boron application (control), T2 a single foliar spray of 0.5% boron during the vegetative stage, and T3 two foliar applications of 1.5% boron during the vegetative and pod-forming stages. Boron application significantly increased several growth and yield parameters, including plant height, number of leaves per plant, number of branches per plant, root length, inflorescence length, number of siliquae per plant, number of seeds per siliqua, seed yield, stover yield, 1000-seed weight, biological yield, and harvest index. The T3 treatment produced the highest number of siliquae per plant (121.15), seeds per siliqua (11.75), stover yield (1641.69 kg ha-1), and 1000-seed weight (3.25gm), seed yield (1035.37 kg ha-1). However, the plant population was not substantially impacted by the various boron treatments. In terms of the phytochemical makeup, the study discovered that among the treatments, boron had no significant effect on the total phenolic and total flavonoid contents. Total flavonoid content ranged from 17.05 mg Qe/g to 15.99 mg Qe/g, and total phenolic content ranged from 14.97 mg GAE/g to 14.71 mg GAE/g. Further studies involving different mustard varieties and growing conditions are recommended to better understand the effect of boron as a micronutrient.