Rapid attentional orienting toward relevant stimuli and efficient disengagement from irrelevant stimuli are critical for survival. Here, we examined the roles of memory processes, emotional arousal and acute stress in attentional disengagement. To this end, 64 healthy participants encoded negative and neutral facial expressions and, after being exposed to a stress or control manipulation, performed an attention task in which they had to disengage from these previously encoded as well as novel face stimuli. During the attention task, electroencephalography (EEG) and pupillometry data were recorded. Our results showed overall faster reaction times after acute stress and when participants had to disengage from emotionally negative or old facial expressions. Further, pupil dilations were larger in response to neutral faces. During disengagement, our EEG data revealed a reduced N2pc amplitude when participants disengaged from neutral compared to negative facial expressions when these were not presented before, as well as earlier onset latencies for the N400f (for disengagement from negative and old faces), the N2pc, and the LPP (for disengagement from negative faces). In addition, early visual processing of negative faces, as reflected in the P1 amplitude, was enhanced specifically in stressed participants. Our findings indicate that attentional disengagement is improved for negative and familiar stimuli and that stress facilitates not only attentional disengagement but also emotional processing in general. Together, these processes may represent important mechanisms enabling efficient performance and rapid threat detection.