Background: The study aimed to investigate novel biomarkers from the C1q TNF superfamily and evaluate their role in autoimmune inflammatory rheumatic diseases with the goal of identifying an effective biomarker to measure clinical disease activity and assess treatment efficacy. Methods: Sixty-one Axial spondyloarthritis (AxSpa) patients and 30 healthy controls were enrolled in the study. The serum biomarkers subfatin, CTHRC1, CTRP3, CTRP6, IL-6, IL-17, and TNF-α and the disease indices BASDAI, BASFI, MASES, and ASDAS–ESR/CRP were evaluated and compared. The patients were then classified, and their serum biomarkers were assessed according to their ASDAS scores and their treatment regimens. Results: Among the studied biomarkers, none showed a significant difference between the patients and the healthy controls. Although the difference was not statistically significant, the median values of serum subfatin, CTHRC1, CTRP3, CTRP6, IL-6, IL-17, and TNF-α were all found to be lower in the AxSpa patients than in the healthy controls. Furthermore, once the patients were classified regarding their disease activity, no correlation between the study biomarkers and levels of clinical disease indices was observed. Finally, biological treatments were found to affect the serum concentration of these biomarkers regardless of the level of disease activity. Conclusion: Novel adipokines and known modulators of inflammation, circulating subfatin, CTHRC1, CTRP3, CTRP6, IL-6, IL-17, and TNF-α levels may play a role in assessing treatment efficacy, especially in those treated with TNF-inhibitors. However, we failed to demonstrate a correlation between clinical disease activity and serum biomarker levels.