This study aimed to investigate the associations between social isolation, loneliness, and motoric cognitive risk syndrome (MCR) among older adults in China. Data were obtained from the China Health and Retirement Longitudinal Study in the 2011 and 2015 waves. Social isolation and loneliness were measured by an index and an item, and MCR was defined as subjective cognitive complaints and slow gait. Multivariable logistic regression analyses were performed to examine the associations between social isolation, loneliness, and MCR by gender. Of 3251 eligible participants, the incidence of MCR was 10.03%. Social isolation and loneliness were not significantly associated with incident MCR in men. Loneliness was positively associated with incident MCR in women (OR: 1.45, 95% CI: 1.05, 2.01), while social isolation was not. Loneliness is associated with incident MCR among female older adults in China. More attention is advised to be paid to loneliness among female older adults, to hold promise for the prevention and reduction of MCR.