The combined effect of full (spew) fillet formed bi-adhesive and parallel slot in adherend on the stress distribution along the length of adhesive bonded single lap joint (SLJ) was investigated using the finite element (FE) method under pure tension (i.e. twenty parallel slots of dissimilar length and depth and two types of bi-adhesive bonds). The FE model of the joints that had fillet, parallel slot and bi-adhesive bondline was developed. In this study, it is assumed that both adhesive and adherend have geometrical nonlinearity and exhibit linear material behavior. The bondline behavior of bi-adhesively bonded joints has been studied by examining the distributions of the peel and maximum principal stresses at the mid-plane of the bondline. The novelty of this study is to investigate the bondline behavior of fillet formed SLJ with the integration of parallel slot mechanism. The results of the numerical computation show that the combined use of the parallel slot and spew fillet on bi-adhesively bonded lap joint decreased the peak value of the peel and maximum principal stresses markedly. The improvement of the strength properties of the joints has been acquired from the studies in which varying geometric parameters are used. This model may be beneficial to enhance the strength of aluminum SLJ.