In addition to voluntary goals and stimulus salience, a stimulus’ prior associated reward also influences selective attention. Previous studies have demonstrated that previously reward-associated auditory stimuli can affect a later visual task, even as such stimuli become task irrelevant. We show that the same can happen the other way around, as task irrelevant reward-associated visual stimuli interferes with the performance of an audiovisual task. This interference negatively correlates to synchronization in simultaneously acquired electroencephalography (EEG) data with the auditory signal, expressed by increased inter trial phase coherence measures. EEG analyses showed that both reward and uncertainty associations jointly modulated neural synchronization. Through behavioral and neural data, our findings suggest that value-driven cross modal attentional capture dynamically interferes with visual and auditory processes. Interference occurs under increasing neural synchronization to a contextually irrelevant reward-associated signal dynamics. The results thus specify an additional cross-modal modulation directionality, and provide further evidence of the relevance of reward uncertainty for such effects.