Objective: ADHD is a neurodevelopmental condition associated with elevated symptoms of inattention and hyperactivity/impulsivity. Symptoms of ADHD typically persist into adulthood and can impair functioning and overall quality of life. In females (including women and people assigned female at birth), ADHD is under-recognized, and knowledge about the relationship between ADHD symptoms and sex hormones is lacking. This systematic review aimed to synthesize the current evidence investigating the relationship between ADHD symptoms (including medication effects) and sex hormones in females. Method: Searches were conducted within Ovid MEDLINE, Embase, and PsycINFO from 1980 to January 2025. Included studies investigated ADHD symptoms in the context of hormonal changes in females, including studies specifically exploring ADHD and sex hormones, as well as hormonal life stages (puberty, menstrual cycle, and pregnancy). Narrative synthesis was utilized for data extraction, grouping studies by hormonal phase. Results: A total of 11 studies were included in this review. Evidence was largely suggestive of a relationship between ADHD symptoms and sex hormones in females, specifically in puberty and across the menstrual cycle. Findings were limited by the small number of studies reviewed, often with small sample sizes and considerable diversity in participant populations and outcome measures. Conclusion: Sex hormones and phases related to hormonal changes (such as puberty and the menstrual cycle) may be associated with ADHD symptom changes in females. Further research is needed to understand the relationship between sex hormones and ADHD symptoms and requires investigation of a wider range of hormonal milestones in females, including menopause.