The platform business model is becoming increasingly dynamic due to the growth of the gig economy, which employs algorithmic management to manage and control its workforce. The absence of human managers has caused significant changes to the controller-controlee relationship, resulting in workers struggling to comprehend the complexity of algorithmic decision-making and control. This, in turn, leads to technical opacity and power asymmetry, with workers increasingly engaging in sensemaking to make sense of algorithmic management practices and to dismantle algorithmic"black boxes." We discovered 13 sensemaking behaviors that capture how food delivery workers understand algorithmic management practices, categorizing them into micro and macro sensemaking, and exploring them in the context of organizational power, opacity, and isolation. By examining the impact of algorithmic technology on sensemaking and analyzing how gig workers make sense of the new controller-controlee relationship, we offer theoretical implications for sensemaking theory and contribute to a better understanding of workers' reactions to algorithmic management practices.