First responders are routinely exposed to traumatic events that can affect their mental health to the extent of suicidal ideation and suicide completion. The purpose of our study is to inform the comparability of predictors of suicidality across first responder types to elucidate the most efficacious targets for intervention and clinical intercession. Clients (N = 224) sought counseling services between 2015 and 2020 at a not-for-profit organization. We conducted a matched study with cases defined as those with suicidality at baseline and those without suicidality at baseline (controls). First responder types were law enforcement officers (LEOs), firefighters, and emergency medical technicians. Clients were mostly LEOs (41.5%), followed by firefighters (29.9%) and emergency medical technicians (28.6%). Logistic regression models tested the relationship between mental health measures and suicidality. All measures of mental health constructs varied significantly across those with or without suicidality and differed across first responder subtype. Depression and posttraumatic stress disorder were significant predictors of suicidality for both LEOs and firefighters. Alcohol/substance misuse was only a significant predictor among LEOs. Resilience was a protective factor for both LEOs and emergency medical technicians. Specific differences in predictors of suicidality across first responder subtypes may enable occupation-specific targets for mental healthcare.