Objective To examine the effect of a mass media campaign designed to increase bowel cancer screening participation. Methods We assessed weekly participation, from January 2015 to December 2017, in the Australian National Bowel Cancer Screening Program in Victoria, where a seven-week campaign aired in mid-2017, and in the adjacent comparison state of South Australia. Participation, defined as the number of immunochemical faecal occult blood tests returned out of those invited by the Screening Program in the past 16 weeks, was analysed using negative binomial regression. Results Compared with non-campaign weeks, there was an increase in the return rate in the campaign state during campaign weeks (adjusted return rates non-campaign weeks = 34.4% vs. campaign weeks = 45.3%, p < 0.01), not observed in the comparison state (38.3% vs. 40.3%, p > 0.05). The increase in the return rate was significantly greater in the campaign state (Rate Ratio of Campaign/Non-Campaign weeks = 1.31, p < 0.01) than the comparison state (1.05, p > 0.05, interaction p < 0.001), and did not differ significantly by age, sex or socio-economic area. The relative increase was greater among never-participants (Rate Ratio of Campaign/Non-Campaign weeks = 1.24) than previous-participants (1.16), interaction p < 0.001). Conclusions This mass media campaign increased bowel cancer screening participation, including from never and low participation subgroups. To maximize participation and ensure equitable population benefit, repeated campaigns that reach eligible people about bowel cancer risks and potential life-saving benefits of screening should be standard.