Background: Media guidelines can influence suicide-related reporting quality and may impact suicide rates. Aim: Our study aimed to investigate the quality of suicide-related reporting after the release of the 2009 Canadian Psychiatric Association (CPA) guidelines and their impact on suicides. Method: A random sample of suicide-related articles (n = 988) were retrieved from 12 major Canadian print/online publications (2002–2015). Articles were coded for quality of content before and after guidelines release. Suicide mortality data were obtained from Ontario coroner records. Time series analyses were used to identify associations between guideline publication and subsequent suicides. Results: The CPA guidelines were associated with improvements in reporting quality with 10 putatively harmful elements being less frequent after their publication. These included less frequent front-page articles, monocausal (simplistic) explanations for suicide, and depictions of suicide methods. Two putatively protective factors, alternatives to suicide and messages of hope, were twice and four times as common, respectively, after the guidelines. The guidelines were not associated with a change in suicide counts. Limitations: This study could not prove exposure to suicide reporting. Conclusion: Publication of Canadian media guidelines was associated with significant, moderate-sized improvements in reporting quality but not with decreased suicides. The latter finding may reflect only modest dissemination and implementation of the guidelines.