Purpose To explore the effects of mobile health (mHealth) intervention on pregnancy weight management, blood glucose control and pregnancy outcomes. Methods A total of 124 patients with gestational diabetes mellitus (GDM) were selected. Patients were randomly divided into two groups. The 60 patients in the control group received standard outpatient treatment, while the remaining 64 patients received a nurse’s online guidance both through a mobile medical App installed on their phone and through regular offline clinical treatment in the mHealth group. Patients were treated for an average of 13 weeks and general conditions, compliance, blood glucose, glycosylated hemoglobin, weight gain, pregnancy, and neonatal outcomes were monitored in both groups longitudinally. Results The mHealth group demonstrated higher levels of compliance (83.3 ± 12.5% vs. 70.4 ± 10.1%, t  = − 6.293, df  = 122, p  < 0.001), lower frequency of outpatient service (8.1 ± 1.3 vs. 11.2 ± 1.1, t  = 14.285, df  = 122, p  < 0.001), lower hemoglobin A1C before delivery (4.7 ± 0.2 vs. 5.3 ± 0.3, t  = 13.216, df  = 122, p  < 0.001) as well as the rates of off-target measurements both fasting (4.6 ± 0.4% vs. 8.3 ± 0.6%, t  = 40.659, df  = 122, p  < 0.001) and 2 h post-prandial (7.9 ± 0.7% vs. 14.7 ± 0.8%, t  = 50.746, df  = 122, p  < 0.001). Weight gain in the mHealth group was less than control group (3.2 ± 0.8 vs. 4.8 ± 0.7, t  = 11.851, df  = 122 p  < 0.001). Conclusion Mobile health intervention management of gestational diabetes mellitus improves patients’ compliance and blood glucose control, and reduces weight gain, thereby reducing the rates of complications in both pregnant women and fetuses during delivery during pregnancy.