Motivational interviewing with parents in the maternity ward in the days following childbirth is feasible and effective in the French context for reducing vaccine hesitancy and increasing the intention to vaccinate their child at 2 and 12 months. This supports the need for an implementation research phase to study the conditions for scaling up the intervention beyond the research setting. This study was conducted in two maternity wards via a randomized controlled trial comparing the impact of a motivational interview conducted by a midwife (intervention group) to that of distributing a brochure on vaccination (control group) on mothers’ vaccine hesitancy (VH) and their intention to vaccinate (IV) their child. Compared to the control group, the motivational interview resulted in a greater reduction in VH of 6 points on a scale of 0 to 100 and a greater increase in VI of 0.6 points on a scale of 0 to 10. These differences between the two groups persisted at 7 months (a reduction of 7.2 points/100 for VI and an increase of 0.8 points/10 for I, in favor of motivational interviewing). Satisfaction rates among mothers who received the interview were over 95% across all indicators, including the timing of the intervention.