The past few years have witnessed power conversion efficiency (PCE) of organic solar cells (OSCs) skyrocketing to the value of 20% due to the outstanding advantages of organic photoactive materials. The latter, which consist of donor and acceptor materials, indeed play important roles in OSCs, and particularly one building block has attracted considerable research attention, namely benzothiadiazole (BT). The diversity of OSCs based on the BT structure have indeed sprung up, and the progressive increase in PCE values is more than just eye-catching since it heralds a renewal and bright future of OSCs. This review analyzes significant studies that have led to these remarkable progresses and focuses on the most effective BT smallmolecules and BT polymers for OSC reported in the last decades. The pivotal structure-property relationships, donor-acceptor matching criteria, and morphology control approaches are gathered and discussed in this paper. Lastly, we summarize the remaining challenges and offer a personal perspective on the future advance and improvement of OSCs.