Cabotegravir (CAB-LA), the first long-acting injectable pre-exposure prophylaxis (PrEP), has been approved for use in the USA and is not currently on the market in China. However, willingness to use CAB-LA and associated factors among men who have sex with men (MSM) have not yet been evaluated in China. A cross-sectional study was conducted in Guangxi, China, in 2022 recruiting 1,006 MSM. Their mean age was 30.2 years, 74.2% had college or above education, and 48.6% had a monthly income between 3,000 and 5,999 Chinese yuan (CNY). Most (73.4%) had previously heard of PrEP while few (8.3%) had ever used this type of preventative medication. Willingness to use CAB-LA was 79.8% and was positively associated with eight variables: younger age, being married to a woman, having a low monthly income, having six or more male partners in the past six months, having only regular male partners in the past month, having a high perceived risk of HIV infection, and history of using PrEP. Ten other variables were not significantly associated with willingness to use CAB-LA. Among 894 participants who were willing to use or did not definitely reject using CAB-LA, the main concerns about CAB-LA were its side effects (90.2%), efficacy (63.6%), and high cost (58.2%). Only 14.7% were willing to pay more than 1,200 CNY (~US$180) every two months to use CAB-LA. The preferred injection places were centers for disease control facilities, hospitals, and social organizations. Many (89.0%) said that they would recommend CAB-LA to their male sexual partners. We conclude that willingness to use CAB-LA was high among MSM in Guangxi. However, implementation of CAB-LA faces tough challenges due to its high cost and the low use of PrEP. Peer education may play a large role in the implementation of CAB-LA in China.