This umbrella review of systematic reviews and meta-analyses investigated the effect of continuous positive airway pressure (CPAP) on blood pressure in patients with obstructive sleep apnea (OSA). It included 17 reviews, with a citation matrix analysis showing a corrected coverage area of 14.2%, indicating significant overlap of primary studies. According to the AMSTAR-2 assessment, only 3 reviews were of high quality, while 14 (82.3%) were of low quality due to lack of registered protocols, inadequate consideration of risk of bias and poor reporting of funding. The GRADE certainty of evidence was high for 4 outcomes, moderate for 29, low for 51, and very low for 25. CPAP therapy is associated with modest reductions in blood pressure, particularly nocturnal, and is generally well tolerated without serious adverse effects. Findings should be interpreted with caution due to low certainty of evidence, methodological flaws, and overlapping studies.