This study aims to test the efficacy of text messaging cues (SMS) to promote physical activity (PA) habit formation in the workplace. Employees (N = 49; 28 females and 21 males, Mage = 47.5 ± 8.29 years) were randomized into two parallel groups: a PA group enrolled in a 28-week supervised PA program and a PA+SMS group enrolled in the same PA program with text messaging cues received before their PA sessions. The exercise habit was assessed every week from self-reports on an online application. PA maintenance and several physical fitness measures were also assessed prior to and after the intervention to evaluate its general impact. Mixed model analysis of the 603 observations indicated a small but significant effect of the SMS cues on the speed at which participants engaged in PA behaviors, as the significant interaction effect revealed that the slope of the exercise habit over time was slightly steeper in the PA+SMS group (B = 0.0462, P = 0.0001) than in the PA group (B = 0.0216, P = 0.01). SMS delivery had a marginal effect on the maintenance of PA behaviors 1 year after the intervention. The results suggest that text messaging can help to form PA habits at the workplace and might facilitate long-term maintenance of PA behaviors.