Masked hypertension (MH) and masked uncontrolled hypertension (MUH) remain largely underdiagnosed with no efficient detection algorithm. We recently proposed a novel classification of office systolic hypertension phenotypes defined on the basis of both brachial and aortic systolic blood pressure (bSBP/aSBP) and showed that type III ("isolated high office aSBP" phenotype: normal office bSBP but high office aSBP) has higher hypertension-mediated organ damage (HMOD). We tested whether MH/MUH (1) can be detected with the "isolated high office aSBP" phenotype and (2) if it is associated with elevated office aSBP with respect to normotension. We classified two separate and quite different cohorts (n = 391 and 956, respectively) on the basis of both bSBP and aSBP into four different phenotypes. Participants were classified as sustained hypertensives, masked hypertensives/masked uncontrolled hypertensives (MHs/MUHs), white coat hypertensives, and normotensives according to their office and out-of-office BP readings. The majority (more than 60% in cohort A and more than 50% in cohort B) of type III individuals were MHs/MUHs. Almost 35% of MHs/MUHs had optimal office bSBP rather than high normal bSBP. In both cohorts, the detection of more than 40% of MH/MUH was feasible with the type III phenotype. MHs/MUHs had higher office aSBP than individuals with sustained normotension (p < 0.05). In conclusion, in the absence of an efficient screening test, the diagnosis of MH/MUH can be assisted by the detection of the "isolated high office aSBP" phenotype, which can be measured in a single office visit. MHs/MUHs have increased aSBP relative to normotensives, further explaining the increased mortality of MH/MUH.