Introduction: Prior research examining self-awareness of deficits in those with mild cognitive impairment (MCI) has been inconsistent, suggesting that preservation of insight at this disease stage may be conditional on the domain(s) examined as well as individual characteristics. The current study is the first to examine differences in objective performance and self-awareness of difficulties between older adults with amnestic single- (MCI–ASD) and multidomain MCI (MCI–AMD) across six instrumental activities of daily living (IADLs). Method: Seventy-five individuals (M age = 73.9 years, range = 55–88 years; 56% female) with MCI–ASD (n = 30) and MCI–AMD (n = 45) were recruited primarily from a hospital-based memory disorders clinic. Participants were administered self-report and objective measures assessing six functional domains: financial management, driving, telephone use, nutrition evaluation, grocery shopping, and medication management. Self-awareness discrepancy scores were calculated for each of these IADLs, and participants were classified as either “overestimating ability” or “accurately/underestimating ability.” Results: Individuals with MCI–AMD performed significantly worse on objective measures of financial management, driving, and nutrition evaluation than those with MCI–ASD. Across MCI subtypes, participants were most likely to lack awareness of their difficulties in nutrition evaluation (31%), financial management (25%), and driving (23%) domains. Individuals with MCI–AMD were significantly more likely than those with MCI–ASD to overestimate performance on driving and telephone use domains. Conclusion: Individuals with MCI–AMD are more likely than those with MCI–ASD to have impairment in their everyday function and to lack awareness into their IADL difficulties. When possible, clinicians should obtain objective measures in combination with detailed informant reports of functional abilities in order to evaluate capacity to independently engage in various daily activities. Finally, level of self-awareness varies across IADL domains, providing further evidence that insight is not a unitary construct.