Despite the availability of guidelines and protocols, service users' experiences of accessing care and treatment for self-harm and suicidal ideation at the Emergency Department (ED) are variable. There is a need to better understand what impacts service user experiences given the important role of the ED for accessing care and influencing future interactions with mental health services for people who experience self-harm and suicidal distress. This study aimed to identify the experiences of service users when presenting to the ED with self-harm and suicidal ideation. A descriptive qualitative approach was utilised encompassing in depth semi-structured interviews with 50 adult service users who attended EDs across the Republic of Ireland for self-harm and suicidal ideation. Data were analysed using reflexive thematic analysis. Findings are reported in accordance with COREQ guidelines and focus on three themes that were developed from the data: (1) Experiences of assessment, (2) Interpersonal interactions, (3) Discharge, onward referral and next steps to care. Participant experiences of care and treatment in the ED were largely negative with reports of an over-reliance on mechanistic assessments, poor interpersonal interactions and lack of support following discharge from the ED. The use of evidence-based protocols is important to ensure standardised and effective care and treatment of people attending the ED with self-harm and suicidal ideation. However, a relational approach needs to underpin their use to ensure that service users feel respected and listened to by all staff in the ED, and more positively inclined towards future help-seeking.