Objective: A new series 2-phenyl-3-(substituted benzo[d] thiazol-2-ylamino)-quinazoline-4(3H)-one was prepared by the fusion method by reacting 2-phenyl benzoxazine with 2-hydrazino benzothiazole and it was evaluated for their antimicrobial activity against gram positive, gram negative bacteria and fungi.Methods: Titled compounds were synthesized by fusion reactions. These compounds were evaluated by in vitro antibacterial and antifungal activity using the minimum inhibitory concentration and zone of inhibition methods. The synthesized compounds were characterized with the help of infrared, NMR and mass spectral studies. The benzothiazole moiety and the quinazoline ring have previously shown DNA gyrase inhibition and target related antibacterial activity. Thus, molecular docking studies of synthesized compounds were carried out (PDB: 3G75) to study the possible interaction of compounds with the target. The batch grid docking was performed to determine the probable.Results: These compounds showed significant activity against gram positive and gram negative bacteria as well against the fungi. The compound A5 was found to be active against B. subtilis, P aeruginosa and C. albican at 12.5 µg/ml MIC. The compound A3 was found to be active against all microbial strains selected at 25 and 12.5 µg/ml MIC.Conclusion: Though the relationship between the activities shown by these compounds in, the antimicrobial study is still to be established, the docking studies conducted found to be consistent with antimicrobial results. Thus the results indicate that the designed structure can be a potential lead as an antimicrobial agent.