Preoperative anxiety before cesarean section is a major issue. Nonpharmacologic anxiety control is believed to be more suitable in pregnant women. Auricular acupuncture (AA) is an inexpensive, easy-to-use, and validated intervention to reduce anxiety in different surgical settings. We evaluated the effect of AA on preoperative cesarean section anxiety. In a prospective, blind, controlled trial, pregnant women with a scheduled cesarean section under spinal anesthesia were randomized to receive AA with needle, AA without needle (sham), or usual care (no intervention). Anxiety level was assessed by using a visual analogue scale for anxiety (VAS-A; 0-minimal anxiety, 100-maximal anxiety) at three time points: inclusion (pre-induction room-T0), when entering the operating room (T1), and before incision (T2). The primary outcome was the VAS-A variation (percentage changes) between T0 and T1 in the AAe group compared with that in the sham AA group. The secondary outcomes were the VAS-A variation between T0 and T1 in the AA group compared with that in the control group, and the variation between T0 and T2 compared between the three groups, the effect of AA on parasympathetic tone, and the incidence of adverse effects. In women immediately before anesthesia for cesarean section, the AA produced a 19% decrease of anxiety, compared with a 21% anxiety increase in sham AA, which is significantly different. The effect of AA was more present in women with low initial anxiety. The proportion of patients reaching clinically significant anxiety reduction (>33% from the initial level) was 2.5 times higher in the AA group ( = 0.02) compared with the sham group. No differences in anxiety variations were found compared with the no-intervention group. No effect of AA was noted on parasympathetic tone. Compared with sham, AA decreased maternal anxiety level when arriving in the operation room and just before the beginning of the cesarean section, with a trend toward improvement compared with usual care.