Mixed-reality (MR) technology has been widely used to simulate high-risk workplaces in order to minimize safety concerns. However, its use in understanding worker attentional allocation during interactions with drones in future construction environments remains underexplored. This study developed a futuristic bricklaying MR environment, where human-drone interaction was mandatory, to capture participants’ naturalistic behaviors (i.e., attention, productivity, and distraction) across different interaction levels (i.e., no interaction, coexistence, and collaboration). The core research question explored whether workers maintained situational awareness of the drones or were distracted by them. The results confirmed that participants experienced a high sense of presence in the MR environment, driven by the use of environmental modalities, passive haptics, and drones’ sounds and spinning blades. Moreover, the findings demonstrated that participants were distracted by the drones during coexistence, as evidenced by lower productivity and reflections indicating they felt they were over-allocating attention to the drones. Conversely, participants exhibited situational awareness of the drones during collaboration, deliberately allocating attention to ensure safety, despite a reduction in productivity. These findings highlight the value of immersive technology in investigating workers’ naturalistic behaviors in future construction scenarios where workers and robots must function as teammates.