Introduction The new channels of communication as social media (e.g. Facebook and Twitter) and the social marketing campaign (i.e. campaign focused on enabling, encouraging and supporting behavioural changes among target audiences) can represent useful strategies to challenge stigma attached to mental disorders. Objectives To evaluate the efficacy of the social marketing campaign of the time to change (SMC-TTC) anti-stigma programme on the target population in England during 2009–2014. Aims To assess the impact of the SMC-TTC anti-stigma programme in terms of: – use of the social media channels; – levels of awareness of the SMC-TTC; – changes in knowledge, attitude, and behaviour related to mental disorders. Methods Participants completed the mental health knowledge schedule (MAKS), the community attitudes toward mental illness (CAMI) and the reported and intended behaviour scale (RIBS), together with an ad-hoc schedule on socio-demographic characteristics. Results In total, 10526 people were interviewed, it was found a growing usage of the SMC-TTC media channels and of the level of awareness of the campaign (P < 0.001). Being aware of the SMC-TTC was found to be associated with higher score at MAKS (OR = .95, CI = .68 to 1.21; P < .001), at “tolerance and support” CAMI subscale (OR = .12, CI = .09 to .16; P < .001) and RIBS (OR = .71, CI = .51 to .92; P < .001), controlling for confounders. Discussion In the general population, SMC-TTC has been found to be effective in improving attitudes and behaviours towards people with mental disorders. Conclusions Considering these promising results obtained in England, social media can represent the possible way forward for challenging stigma. The future on-going evaluation of the SMC-TTC may further shed light on the essential role of social media in reducing of stigma and discrimination. Disclosure of interest The authors have not supplied their declaration of competing interest.