Background Armed conflicts severely impact survivors psychologically, with effects tied to the trauma's intensity and widespread displacement. From October 2023 to January 2025, the Gaza Strip faced violent conflict, leading to major displacement and suffering. This study examines anxiety, PTSD, and depression among displaced adults from Gaza Strip. Methods This cross-sectional study, conducted in November 2024, surveyed 952 displaced adults using the GAD-7, PCL-5, and PHQ-9 instruments and a convenience sampling method. A PTSD diagnosis required having a PCL-5 score ≥ 23 and fulfilling the DSM-5 criteria. The rates and severity of probable anxiety, PTSD, and depression were reported. Then, using SPSS, logistic regression models identified factors associated with each disorder, while multinomial regression models explored associations with the number of comorbidities. Results The majority were unemployed (73.7%). Over half of the participants were displaced in camps (55.6%), while 40.4% lived in shelters. Nearly a fifth (20.3%) had lost a first-degree relative, 12.7% were injured, and 4.8% were detained by the military. Moderate or higher levels of anxiety and depression were reported by 79.3% and 84.5%, respectively. The rate of symptomatic PTSD was 67.8% when defined as meeting the DSM-5 criteria for PTSD and having a PCL-5 score ≥ 23, and 88.2% based on the latter criterion alone, while subthreshold PTSD was encountered in 18.1%. Also, 63.1% suffered significant symptoms of all three comorbidities. Significant predictors of anxiety included being female and having PTSD or depression. Significant predictors of PTSD included experiencing more frequent migrations, unemployment or working in the private sector, military detention, or having anxiety or depression. Significant predictors of depression included the death of a first-degree relative, military detention, torture, and having anxiety or PTSD. Additionally, having a higher number of migrations was significantly associated with having one, two, or three disorders compared to having “no disorders,” while those experiencing more forms of harm were significantly more likely to have all three disorders. Conclusions The study found very high rates of psychiatric disorders among IDPs in Gaza and identified several risk factors contributing to those rates. Interventions must be prioritized to support society's long-term recovery.