Our perception of time influences the critical decisions that we make on a daily basis. Time perception may also influence decision making and performance in sport. A lengthened perception of time, such as feeling that one is performing in slow-motion, may be associated with improved sport performance. This experiment reports the first examination of electroencephalographic (EEG) neurofeedback as an intervention designed to lengthen perceived time and improve decision making in sport. Thirty-one participants were randomly assigned to a neurofeedback group or a control group. They completed pre-test and post-test assessments of time perception and decision making in response to soccer penalty video clips played at a variety of speeds. In between, they underwent a 15-min neurofeedback intervention where they were trained to increase EEG theta and alpha power (neurofeedback group) or received sham training (control group). Results revealed that the neurofeedback intervention yielded a selective increase in EEG alpha power among members of the neurofeedback group. However, this had no effect on perception of time, and no beneficial effects on decision accuracy or decision response time. Several interpretations of the possible relationships between time perception, brainwaves and decision making in sport are discussed. Decision response time improved from pre-test to post-test for all participants, evidencing the potential of video-based training as a tool to enhance decision speed. Our findings also establish that just 15-mins of neurofeedback can produce significant changes in EEG alpha power. This highlights the potential of neurofeedback as a time-efficient means of modifying cortical activity for research and applied practice.