A cap with a seamless sweatband is provided and includes a cap body, the seamless sweatband is provided on an inner brim, the seamless sweatband is provided with a sweat-absorbent cotton yarn therein. The seamless sweatband is formed integrally, and fixedly connected to the inner brim of the cap body. The cap with the seamless sweatband is made as a production, which has advantages of convenient processing procedure, lower production costs, higher productivity, more comfort, ventilation, and more convenient use.