diff --git a/README.md b/README.md
index 071dc22..27442e4 100644
--- a/README.md
+++ b/README.md
@@ -129,6 +129,12 @@ heuristic generator remains the fallback.
 
 The FastAPI settings object also accepts `llm_provider` and `llm_model`. By
 default `llm_provider` is unset, so analysis is fully offline and deterministic.
+Environment variables use the `REPO_REGISTRY_` prefix:
+
+```bash
+REPO_REGISTRY_LLM_PROVIDER=gemini
+REPO_REGISTRY_LLM_MODEL=gemini-2.5-flash
+```
 
 ## Agent-Facing Endpoints
 
diff --git a/src/repo_registry/web_api/app.py b/src/repo_registry/web_api/app.py
index cfbe85d..695fe83 100644
--- a/src/repo_registry/web_api/app.py
+++ b/src/repo_registry/web_api/app.py
@@ -5,6 +5,7 @@ from pathlib import Path
 
 from fastapi import Depends, FastAPI, HTTPException
 from pydantic import BaseModel, Field
+from pydantic_settings import BaseSettings, SettingsConfigDict
 
 from repo_registry.core.service import RegistryService
 from repo_registry.llm_extraction import LLMCandidateExtractor, create_llm_connect_adapter
@@ -12,7 +13,9 @@ from repo_registry.repo_ingestion.git import GitIngestionService
 from repo_registry.storage.sqlite import NotFoundError, RegistryStore
 
 
-class Settings(BaseModel):
+class Settings(BaseSettings):
+    model_config = SettingsConfigDict(env_prefix="REPO_REGISTRY_")
+
     database_path: str = Field(default="var/repo-registry.sqlite3")
     checkout_root: str = Field(default="var/checkouts")
     llm_provider: str | None = Field(default=None)
diff --git a/tests/test_web_api.py b/tests/test_web_api.py
index dea7197..5c2f689 100644
--- a/tests/test_web_api.py
+++ b/tests/test_web_api.py
@@ -193,6 +193,20 @@ def test_api_service_settings_can_enable_llm_extractor(monkeypatch, tmp_path):
     assert service.llm_extractor is not None
 
 
+def test_settings_can_load_from_environment(monkeypatch):
+    monkeypatch.setenv("REPO_REGISTRY_DATABASE_PATH", "var/env.sqlite3")
+    monkeypatch.setenv("REPO_REGISTRY_CHECKOUT_ROOT", "var/env-checkouts")
+    monkeypatch.setenv("REPO_REGISTRY_LLM_PROVIDER", "mock")
+    monkeypatch.setenv("REPO_REGISTRY_LLM_MODEL", "demo-model")
+
+    settings = Settings()
+
+    assert settings.database_path == "var/env.sqlite3"
+    assert settings.checkout_root == "var/env-checkouts"
+    assert settings.llm_provider == "mock"
+    assert settings.llm_model == "demo-model"
+
+
 def test_api_analysis_run_loop(tmp_path):
     source = tmp_path / "repo"
     source.mkdir()