diff --git a/model_gateway/src/config/validation.rs b/model_gateway/src/config/validation.rs
index 13639baac..ce168b65f 100644
--- a/model_gateway/src/config/validation.rs
+++ b/model_gateway/src/config/validation.rs
@@ -827,51 +827,44 @@ impl ConfigValidator {
 
     fn validate_urls(urls: &[String]) -> ConfigResult<()> {
         for url in urls {
-            if url.is_empty() {
+            if let Err(reason) = validate_worker_url(url) {
                 return Err(ConfigError::InvalidValue {
                     field: "worker_url".to_string(),
                     value: url.clone(),
-                    reason: "URL cannot be empty".to_string(),
+                    reason,
                 });
             }
+        }
+        Ok(())
+    }
+}
 
-            // Case-insensitive scheme allow-list. Compare just the scheme
-            // segment so we don't allocate a lowercased copy of the full URL.
-            const ALLOWED_SCHEMES: &[&str] = &["http", "https", "grpc", "grpcs"];
-            let scheme = url.split_once("://").map_or("", |(s, _)| s);
-            if !ALLOWED_SCHEMES
-                .iter()
-                .any(|allowed| scheme.eq_ignore_ascii_case(allowed))
-            {
-                return Err(ConfigError::InvalidValue {
-                    field: "worker_url".to_string(),
-                    value: url.clone(),
-                    reason: "URL must start with http://, https://, grpc://, or grpcs://"
-                        .to_string(),
-                });
-            }
+/// Reject empty / schemeless / unparsable worker URLs so callers can wrap the
+/// failure reason in whatever error type fits their layer.
+pub(crate) fn validate_worker_url(url: &str) -> Result<(), String> {
+    if url.is_empty() {
+        return Err("URL cannot be empty".to_string());
+    }
 
-            match ::url::Url::parse(url) {
-                Ok(parsed) => {
-                    if parsed.host_str().is_none() {
-                        return Err(ConfigError::InvalidValue {
-                            field: "worker_url".to_string(),
-                            value: url.clone(),
-                            reason: "URL must have a valid host".to_string(),
-                        });
-                    }
-                }
-                Err(e) => {
-                    return Err(ConfigError::InvalidValue {
-                        field: "worker_url".to_string(),
-                        value: url.clone(),
-                        reason: format!("Invalid URL format: {e}"),
-                    });
-                }
+    const ALLOWED_SCHEMES: &[&str] = &["http", "https", "grpc", "grpcs"];
+    let scheme = url.split_once("://").map_or("", |(s, _)| s);
+    if !ALLOWED_SCHEMES
+        .iter()
+        .any(|allowed| scheme.eq_ignore_ascii_case(allowed))
+    {
+        return Err("URL must start with http://, https://, grpc://, or grpcs://".to_string());
+    }
+
+    match ::url::Url::parse(url) {
+        Ok(parsed) => {
+            if parsed.host_str().is_none() {
+                return Err("URL must have a valid host".to_string());
             }
         }
-        Ok(())
+        Err(e) => return Err(format!("Invalid URL format: {e}")),
     }
+
+    Ok(())
 }
 
 fn validate_mebibyte_limit(field: &str, value_mb: usize) -> ConfigResult<()> {
diff --git a/model_gateway/src/worker/service.rs b/model_gateway/src/worker/service.rs
index 5c6a0cc53..7764f679e 100644
--- a/model_gateway/src/worker/service.rs
+++ b/model_gateway/src/worker/service.rs
@@ -16,7 +16,7 @@ use serde_json::json;
 use tracing::warn;
 
 use crate::{
-    config::RouterConfig,
+    config::{validation::validate_worker_url, RouterConfig},
     worker::{registry::WorkerId, worker::worker_to_info, WorkerRegistry},
     workflow::{Job, JobQueue},
 };
@@ -241,6 +241,8 @@ impl WorkerService {
         &self,
         config: WorkerSpec,
     ) -> Result<CreateWorkerResult, WorkerServiceError> {
+        validate_worker_url_request(&config.url)?;
+
         if self.router_config.api_key.is_some() && config.api_key.is_none() {
             warn!(
                 "Adding worker {} without API key while router has API key configured. \
@@ -431,3 +433,65 @@ impl WorkerService {
         Ok(UpdateWorkerResult { worker_id, url })
     }
 }
+
+/// Wrap [`validate_worker_url`] so the API layer surfaces a 400 instead of a
+/// config-layer error.
+fn validate_worker_url_request(url: &str) -> Result<(), WorkerServiceError> {
+    validate_worker_url(url).map_err(|reason| WorkerServiceError::BadRequest {
+        message: format!("Worker URL '{url}' is invalid: {reason}"),
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn validate_worker_url_request_accepts_all_four_schemes() {
+        assert!(validate_worker_url_request("http://10.0.0.5:8000").is_ok());
+        assert!(validate_worker_url_request("https://10.0.0.5:8000").is_ok());
+        assert!(validate_worker_url_request("grpc://10.0.0.5:8000").is_ok());
+        assert!(validate_worker_url_request("grpcs://10.0.0.5:8000").is_ok());
+    }
+
+    #[test]
+    fn validate_worker_url_request_accepts_case_insensitive_schemes() {
+        assert!(validate_worker_url_request("HTTP://10.0.0.5:8000").is_ok());
+        assert!(validate_worker_url_request("GrPc://10.0.0.5:8000").is_ok());
+    }
+
+    #[test]
+    fn validate_worker_url_request_rejects_bare_host_port_as_400() {
+        let err = validate_worker_url_request("10.0.0.5:8000").unwrap_err();
+        assert!(matches!(err, WorkerServiceError::BadRequest { .. }));
+        assert_eq!(err.status_code(), StatusCode::BAD_REQUEST);
+        assert!(err
+            .to_string()
+            .contains("http://, https://, grpc://, or grpcs://"));
+    }
+
+    #[test]
+    fn validate_worker_url_request_rejects_empty_as_400() {
+        let err = validate_worker_url_request("").unwrap_err();
+        assert!(matches!(err, WorkerServiceError::BadRequest { .. }));
+        assert!(err.to_string().contains("empty"));
+    }
+
+    #[test]
+    fn validate_worker_url_request_rejects_unknown_scheme() {
+        let err = validate_worker_url_request("ftp://10.0.0.5:8000").unwrap_err();
+        assert!(matches!(err, WorkerServiceError::BadRequest { .. }));
+    }
+
+    #[test]
+    fn validate_worker_url_request_rejects_missing_host() {
+        let err = validate_worker_url_request("http://").unwrap_err();
+        assert!(matches!(err, WorkerServiceError::BadRequest { .. }));
+    }
+
+    #[test]
+    fn validate_worker_url_request_rejects_unparsable_url() {
+        let err = validate_worker_url_request("http://[invalid").unwrap_err();
+        assert!(matches!(err, WorkerServiceError::BadRequest { .. }));
+    }
+}