The occurrence of implicit processing of visual stimuli during inattentional blindness is still a matter of debate. To assess the evidence available in this debate, we conducted a systematic review of articles that explored whether unexpected visual stimuli presented during inattentional blindness are implicitly processed despite not being reported. Additionally, we employed meta-analysis to combine 59 behavioral experiments and investigate the statistical support for such implicit processing across experiments. Results showed that visual stimuli can be processed when unattended and unnoticed. Additionally, we reviewed the measures used to assess participants' awareness of the unexpected stimuli. We also employed meta-analysis to search for differences in awareness of the unexpected stimuli that may result from adopting distinct criteria to categorize participants as aware or unaware. The results showed that the overall effect of awareness changed depending on whether more demanding or less demanding measures of awareness were employed. This suggests that the choice of awareness measure may influence conclusions about whether processing of the US is implicit or explicit. We discuss the implications of these results for the study of implicit processing and the role of attention in visual cognition.