Background and Aims Currently, the gasless unilateral axillary approach endoscopic thyroidectomy (GUA-ET) is gradually gaining widespread adoption. However, the creation of the working space has consistently been a challenge in this operation due to the potential risk of damaging crucial blood vessels and nerves during subcutaneous dissection. Our center recently discovered a fat pad located in the supraclavicular fossa (referred to as freedom fat by the authors, abbreviated as F fat) that can be used for tracing the external jugular vein and its tributaries, supraclavicular nerves, and subcutaneous nerve branches during GUA-ET surgery. This study was conducted to determine the clinical application value of using F fat as a guide marker in GUA-ET surgery.Methods The clinical data of 177 patients with papillary thyroid carcinoma who underwent GUA-ET surgery in the Second Ward of the Department of Breast and Thyroid Surgery of Hunan Provincial People's Hospital from May 2022 to December 2022 were retrospectively analyzed. Among them, the F fat was used as a guide marker during surgery in 93 cases (observation group), and was not used during surgery in 84 cases (control group). A comparison was made between the two groups in terms of time for creation of the initial working space, number of cases of bleeding during space creation, rates of conversion to open surgery, and the incidence of complications such as skin burns.Results There were no statistically significant differences in sex and age between the two groups (both P>0.05). The time for the creation of the initial working space in the observation group was significantly shorter than that in the control group [(12.84±2.218) min vs. (30.49±5.871) min, P<0.05]. During the creation of the working space, there were 4 cases of bleeding in the observation group (4.3%) and 6 cases in the control group (7.1%), with no statistically significant difference (P>0.05). No conversion to open surgery required due to intraoperative bleeding and no complications such as skin burns occurred in the observation group, while there were 1 case each of open conversion due to intraoperative bleeding and skin burns in the control group, but the differences were not statistically significant (both P>0.05).Conclusion Using F fat as a landmark to guide GUA-ET surgery can avoid the need of dissection and exposure for protecting structures such as the external jugular vein and its tributaries. This effectively shortens the time for the creation of the initial working space and may also reduce the occurrence of complications. So, it is recommended to be commonly used in clinical practice.