OBJECTIVE: Around the world, the use of modern contraceptives has risen significantly, but the quality and reach of sexual and reproductive health services remains weak in the poorest countries. To address the high unmet need, an opportunity arises for mobile health technology (mHealth) to empower both clients and providers. However, evidence that mHealth is effective in increasing modern contraceptive use is limited and mixed, and we set out to assess its impact. METHODS: A systematic literature search from seven electronic databases was conducted using key search terms. Individually randomised controlled trials that compared modern contraceptive use in women and men using phone message interventions and those without the intervention were included. Stata was used to calculate pooled estimates of effect under the random-effects model, as well as produce the risk of bias using the Egger's regression method. GRADEpro GDT was used to assess the quality of individual studies. RESULTS: A pooled estimate of all of the studies showed a positive association between phone messages and contraception use, but no clear evidence of benefit (OR 1.12; 95% CI 0.97-1.29). Notably, pooled results of studies that reported modern contraceptive use as the primary outcome showed that mobile phone messaging was associated with an increase in the use of modern contraception (OR 1.22; 95% CI 1.01-1.47). CONCLUSIONS: The finding of this systematic review suggests that mobile phone message interventions utilising a behavioural change technique are an effective method of increasing modern contraceptive use among men and women of reproductive age in low- and middle-income countries though the effect is small.