Background The fibrinogen to albumin ratio (FAR) has risen to prominence as a novel biomarker for various conditions, including systemic inflammation. Therefore, this study aims to assess the role of FAR in ankylosing spondylitis (AS) and its correlation with disease activity, severity, and functional status of AS patients. Thirty adult patients with AS were enrolled, along with 20 healthy age- and sex-matched subjects as controls. Bath Indices were used to determine the disease activity, severity, and functional status. Results The patients’ mean age was 35.3 years, including 22 males (73.3%) and eight females (26.7%). The median disease duration was 10 years, ranging from 1 to 28 years. AS cases showed higher FAR than the control group (P < 0.001). Active cases were associated with significantly higher FAR when compared to cases in remission (P < 0.001). FAR showed significant positive correlations with Bath Indices including BASDAI, BASFI, and BASMI scores (P = 0.002, 0.002, < 0.001, 0.019, 0.022). Conclusion FAR has been increased in AS, particularly in active cases. FAR has also been associated with the impaired functional status of AS patients. FAR can represent a novel inflammatory parameter for monitoring disease activity and severity in AS.