Objectives <p>Parenting stress has tremendous impacts on the wellbeing of not only parents but also children and the entire family. To help stressful parents respond more effectively, this study evaluated the acceptability and efficacy of a localized mindful parenting (MP) program in Hong Kong.</p> Methods <p>In this randomized controlled trial, 163 parents (<i>M</i>_age = 42&#xa0;years old; 88% female) with children aged 4–17&#xa0;years and elevated parenting stress were publicly recruited and randomized to receiving the MP program (<i>n</i>_treatment = 83) or simply waiting 16&#xa0;weeks for the treatment (<i>n</i>_{waitlist-control} = 80). Attrition and attendance were tracked. Linear mixed modeling (LMM) was used to examine the program efficacy.</p> Results <p>Attrition from the MP program was 12%. Fifty-eight (70%) parents in the treatment condition completed at least six of the eight sessions. The MP program effected&#xa0;resulted in both immediate and longer-term changes of moderate-to-large sizes in parenting stress, general mindfulness, and mindful parenting. Accounting for natural changes, both the immediate and longer-term effects of the MP program were of small-to-moderate sizes in improving general mindfulness and mindful parenting. Although similar effect sizes were observed for reducing parenting stress beyond natural changes, only the longer-term effect reached statistical significance after adjusting for repeated testing.</p> Conclusions <p>Despite COVID-19-related disruptions, the localized MP program demonstrated acceptability and efficacy among Chinese parents in Hong Kong. Expanding the sample size, diversity within a sample, and measurement methodologies, future research may explore the program’s differential effects by clinical or demographic groups, parenting constructs, and delivery modes.</p> Preregistration <p>This study was approved on 2019–05-03 on the Chinese Clinical Trial Registry (ChiCTR1900022923).</p>