Insomnia is a common health problem in the general population. There are different ways to improve sleeping habits and quality of sleep; however, there is no clinical trial using transdermal neurostimulation to treat individuals with symptoms of insomnia in Asia. This gives us the impetus to execute the first study in Asia, which aims to evaluate the efficacy of electrical vestibular stimulation (VeNS) on individuals with insomnia in Hong Kong. A two-armed, double-blind, randomized, sham-controlled trial was conducted. A total of 101 adults aged 18 to 60 years with insomnia symptoms were recruited in this study. All subjects were computer randomized into either the active VeNS group or the sham VeNS group at a 1:1 ratio. All subjects in each group received twenty 30-min VeNS sessions during weekdays, which were completed in a 4-week period. Baseline measurements (T1) and post-VeNS evaluations (T2) of the psychological outcomes (i.e., insomnia severity, sleep quality, quality of life) were collected for all participants. One-month (T3) and 3-month (T4) follow-up periods were used to assess the short- and long-term sustainability of the VeNS intervention. A total of 83 (40 VeNS and 43 sham-VeNS) subjects participated in this study. VeNS was significantly effective in reducing insomnia severity and improving quality of life (physical limit and emotional limit) immediately poststimulation and at the 3-month follow-up but was deemed ineffective in reducing insomnia severity at 1-month follow-up. VeNS was a novel, noninvasive and safe neuromodulation device that could be considered an adjunct treatment option to treat primary insomnia.