Anxiety disorder can negatively affect many areas of a child’s life, including social and academic development, and increase the risk of mental health problems in adolescence and adulthood. Although psychotherapy is an effective treatment for children with anxiety, it is not widely available, while psychiatric medications are recommended for use in only the most severe cases. For these reasons, investigation into other possible treatments for problems with anxiety is necessary. The present study examined the effect of a broad-based micronutrient formula called EMPowerplus (EMP+) on children suffering from elevated levels of anxiety, following a multiple baseline design. The final sample comprised 14 participants, aged between eight and 12 years, who were randomised into one of three baseline groups, ranging from one to three weeks in length. Following the baseline period, participants took part in an open-label trial of EMP+ for eight weeks, after which a three-month follow-up was conducted. Although there was a trend toward a decrease in symptom severity over the baseline period, there was a much greater decline in symptoms during the intervention phase. Modified Brinley plots revealed decreases in anxiety and improvements in overall functioning for 10 out of 11 participants who completed the intervention. A comparison of group means confirmed statistically significant change between baseline and end of trial, while gains were maintained over the follow-up period. Furthermore, those participants who were compliant with the intervention tended to improve more than participants who were not compliant and side effects were generally mild and transient. This study provides evidence for the potential of micronutrient interventions in effectively treating anxiety in children. It also opens the door for future research utilising placebo-controlled designs, as well as comparisons to other conventional treatments.