Abstract Background The prevalence, prognostic role, and diagnostic value of blood pressure in immune‐mediated thrombotic thrombocytopenic purpura (iTTP) and other thrombotic microangiopathies (TMAs) remain unclear. Methods Using a national cohort of iTTP (n = 368), Shigatoxin‐induced hemolytic uremic syndrome (n = 86), atypical hemolytic uremic syndrome (n = 84), and hypertension‐related thrombotic microangiopathy (n = 25), we sought to compare the cohort’s blood pressure profile to assess its impact on prognosis and diagnostic performances. Results Patients with iTTP had lower blood pressure than patients with other TMAs, systolic (130 [interquartile range (IQR) 118–143] vs 161 [IQR 142–180] mmHg) and diastolic (76 [IQR 69–83] vs 92 [IQR 79–105] mmHg, both p