Vegetative and yield performance of Thevetia peruviana (Pers) Schum. were evaluated under soybean (Glycine max L.) and maize (Zea mays L.) cropping systems during the 2008 and 2009 rainy seasons at the Research Farm of the Biofuel Alternative and Renewable Energy Ltd, Edidi, Kwara State in the Southern Guinea Savanna of Nigeria. The treatment included sole T. peruviana, sole soybean, sole maize, T. peruviana/soybean and T. peruviana/maize cropping systems with T. peruviana plant population of 2,500 plants ha-1. The treatments were laid out in Randomised Complete Block Design (RCBD) with four replicates. Two rows of maize at one plant/stand were planted in each plot assigned for T. peruviana/maize while four rows of maize were planted in each plot assigned for sole maize. Soybean at two plants/stand was planted in each plot assigned for T. peruviana/soybean and sole soybean. Results obtained indicated that T. peruviana/soybean cropping system improved the vegetative growth parameters of the two component crops while T. peruviana/maize cropping system reduced both the vegetative and the yield parameters of the test crop. However the widest stem width was observed under the control T. peruviana. The kernel size of T. peruviana was not significantly affected irrespective of the cropping systems. The kernel yield of T. peruviana under T. peruviana/soybean cropping system increased although statistically similar with sole T. peruviana while the seed yield of soybean under T. peruviana/soybean cropping system significantly increased when compared with the sole soybean. The complimentary use of growth resources such as nutrients, water and light in T. peruviana /soybean cropping system resulted into increase plant height, number of branches and the overall yield of the two component crops. Thus, it can be recommended that for higher yield and sustainability T. peruviana/soybean cropping system is better adopted among the cropping systems.