Pain-related fear and pain catastrophizing are associated with disability and actual performance in chronic pain patients. In acute low back pain (LBP), little is known about the prediction of actual performance or perceived disability by pain-related fear and pain catastrophizing. This experimental, cross-sectional study aimed at examining whether pain-related fear and pain catastrophizing were associated with actual performance and perceived disability. Ninety six individuals with an episode of acute LBP performed a dynamic lifting task to measure actual performance. Total lifting time was used as outcome measure. The results show that pain-related fear, as measured with the Tampa Scale for Kinesiophobia, was the strongest predictor of this physical task. Using the Roland Disability Questionnaire as a measure of perceived disability, both pain-related fear and pain catastrophizing, as measured with the Pain Catastrophizing Scale, were significantly predictive of perceived disability and more strongly than pain intensity was. The results of the current study suggest that pain-related fear is an important factor influencing daily activities in individuals suffering an episode of acute LBP. The study results have important clinical implications, especially in the development of preventive strategies for chronic LBP.