The war in Syria has displaced over 6.8 million people, more than any other conflict since the Second World War. As a result, Syrian asylum seekers and refugees have experienced several life-changing events, resulting in high rates of anxiety, depression, posttraumatic stress disorder, and suicidal ideation (SI). To address the treatment gap and reduce the burden of help-seeking, a web-based intervention to reduce SI developed for general populations was culturally adapted for and with Syrian asylum seekers and refugees in the United Kingdom. The study revealed the importance of understanding their lived experience with migration and the acculturative process in providing treatment for SI. This study will now assess the feasibility and acceptability of the culturally adapted intervention for this population. The first phase of the study will include recruiting participants and delivering the web-based intervention (1) to assess the feasibility of meeting recruitment goals and recruitment rates and (2) to assess the feasibility of outcome measures. The second phase of the study will include one-to-one semistructured interviews (1) to assess the suitability of the culturally adapted intervention in terms of recruitment and adherence rates and barriers and facilitators to engagement and (2) to assess the acceptability of the intervention in terms of its cultural relevance and appropriateness. This is a protocol for a single-group, noncontrolled, mixed methods feasibility and acceptability study of a culturally adapted web-based intervention to reduce SI for Syrian asylum seekers and refugees in the United Kingdom. The study will assess the feasibility of recruitment goals, recruitment rates, adherence rates, and outcome measures using individual participant tracking forms, which will be analyzed quantitatively. The suitability and acceptability of the intervention will be assessed using one-to-one semistructured interviews with 12 participants who completed the intervention, which will be analyzed qualitatively. Recruitment began in February 2024 and will run until 30 participants are recruited to the study or until the end of July 2024. Thus far, 19 participants have provided informed consent, 16 were eligible and enrolled, and 12 have completed a postintervention interview. No data have been analyzed. The study, including the write-up period, is expected to end in December 2024. Despite experiencing several stressors related to forced displacement and high rates of mental health issues, access to treatment is still limited for Syrian asylum seekers and refugees in the United Kingdom. To address the treatment gap and reduce the burden of help-seeking, a web-based intervention to reduce SI was culturally adapted in collaboration with Syrian asylum seekers and refugees in the United Kingdom. This study will now assess the feasibility and acceptability of the intervention and culturally appropriate recruitment strategies. ISRCTN ISRCTN11417025; https://www.isrctn.com/ISRCTN11417025. PRR1-10.2196/56957.