Background Having inadequate health care systems and poor socio-economic infrastructure, Bangladesh has been braving to contain the impact of current COVID-19 pandemic since March, 2020. To curb the diffusion of COVID-19, the local government has responded to the outbreak by enforcing a set of restricted measures on economic and social activities across the country. Objectives Here, we aim to assess the propagation of COVID-19 by estimating the coronavirus active cases and mortality rate in two major business hubs of Bangladesh, namely Dhaka and Chittagong city under flexible lockdown conditions. Methods We apply a data-driven forecasting model using Susceptible, Exposed, Infected, Recovered and Deaths status through time to deal with coronavirus outbreak. Results The epidemiological model forecasts the dire consequences for Dhaka city with 2400 death cases at the end of December, 2020, whereas Chittagong city might experience 14% more deaths than Dhaka if the severe restrictions are not implemented to control the pandemic. Conclusion Although lockdown has a positive impact in reducing the diffusion of COVID-19, it is disastrous for human welfare and national economies. Therefore, a unidirectional decision by the policymakers might cost a very high price on either way for a lower-middle-income country, Bangladesh. In this study, we suggest a fair trade-off between public health and the economy to avoid enormous death tolls and economic havoc in Bangladesh.