Recently, arsenene, having a monolayer honeycomb structure of grey arsenic, has been manufactured successfully. Motivated by this, here we have calculated the electronic properties and stability of arsenene by employing the first-principles method for calculations. We have considered two different structures, namely planar and puckered. Based on the analysis, the puckered structure was found to be semiconducting in nature. Additionally, we have estimated the electronic properties of different 3d transition metal (TM) atoms doped in arsenene. Here, straining the nanoribbons also modulates the band gap. It closes the band gap for puckered arsenene under the 8% strain application. Specifically, a 4% strain is considerably sufficient to transform metallic arsenene to a direct band-gap semiconductor. Also, the bond angle between the nearest atoms becomes almost equal. We have observed that Ni-doped arsenene is the most stable. We have also studied the electronic band structures of the pristine and TM-doped antimonene. Planar antimonene is metallic while rhombohedral antimonene is semiconducting. Our results will play vital roles in sensors and various nanoelectronics applications.