Online social networking interventions have potential to support young people who experience suicidal thoughts by specifically addressing interpersonal risk factors for suicide, but may also pose a risk of harm. This uncontrolled, single-group pilot study aimed to evaluate the safety, feasibility, and acceptability of an enhanced online social networking intervention (“Affinity”) among a sample of young people who experienced active suicidal ideation, and to explore potential changes in clinical outcomes and the therapeutic targets of the intervention. Twenty young people with current or recent suicidal ideation who were receiving treatment for depression at a tertiary-level mental health service were given access to Affinity for two months. Participants were assessed at baseline and 8-week follow-up; 90 percent reported clinical suicidal ideation at baseline. A priori criteria related to feasibility, safety and acceptability were satisfied. In terms of potential clinical effects, significant and reliable pre-post improvements were found on self-report outcomes including suicidal ideation. This study provides initial world-first evidence to support the use of an online intervention incorporating social networking as an adjunct to treatment for young people who experience suicidal ideation. The effectiveness of Affinity needs to be evaluated in a randomised controlled trial.