Objectives: There is a need to examine the utility of objective measures of attention-deficit/hyperactivity disorder (ADHD) symptoms in children. Objective measures of ADHD symptoms, such as physical activity, may provide a more nuanced assessment of behavior that can be used to augment traditional cross-informant ratings of ADHD symptoms by parents and teachers. The most widely used and researched technique for objectively capturing children's physical activity is accelerometry (i.e., the use of small devices that measure gravitational acceleration). The current study examined the unique and interactive effects of mean levels of physical activity (physical activity volume) and intra-individual variability in physical activity (physical activity variability), as measured by accelerometry, on teacher-reported ADHD symptoms (hyperactivity/impulsivity and inattention examined separately). Method: One hundred seventy-six early elementary school students (M[subscript age] = 6.83, SD = 0.96, 53% male) from four midwestern schools and four northeastern schools were included. All were participants in a before-school intervention study involving physical activity or a sedentary classroom program. Data were collected using accelerometry during the intervention period and ADHD symptoms were reported by teachers following the intervention. Multiple regression models were used to examine the unique and interactive effects of physical activity volume and physical activity variability on ADHD symptoms. Results: Results demonstrated that physical activity volume was positively associated with hyperactive/impulsive symptoms, whereas physical activity variability was negatively associated with hyperactive/impulsive and inattentive symptoms. Additionally, when both physical activity variables were in the same model, only physical activity variability uniquely predicted ADHD symptoms after accounting for physical activity volume. Specifically, higher physical activity variability was linked with lower hyperactive/impulsive and inattentive symptoms. Conclusion: Objective measures of physical activity volume and physical activity variability may enhance our understanding of physical activity patterns as they relate to ADHD symptoms. Future research should continue to investigate the usability of objective measures of physical activity, and especially physical activity variability, as a screener to identify children at risk for ADHD.