diff --git a/lib/ruby_llm/providers/openrouter.rb b/lib/ruby_llm/providers/openrouter.rb
index e8056b027..e80282085 100644
--- a/lib/ruby_llm/providers/openrouter.rb
+++ b/lib/ruby_llm/providers/openrouter.rb
@@ -16,6 +16,35 @@ def headers
         }
       end
 
+      def parse_error(response)
+        return if response.body.empty?
+
+        body = try_parse_json(response.body)
+        case body
+        when Hash
+          parse_error_part_message body
+        when Array
+          body.map do |part|
+            parse_error_part_message part
+          end.join('. ')
+        else
+          body
+        end
+      end
+
+      private
+
+      def parse_error_part_message(part)
+        message = part.dig('error', 'message')
+        raw = try_parse_json(part.dig('error', 'metadata', 'raw'))
+        return message unless raw.is_a?(Hash)
+
+        raw_message = raw.dig('error', 'message')
+        return [message, raw_message].join(' - ') if raw_message
+
+        message
+      end
+
       class << self
         def configuration_requirements
           %i[openrouter_api_key]
diff --git a/spec/fixtures/vcr_cassettes/providers_openrouter_parse_error_with_openrouter_openai_o3-mini_raises_detailed_error.yml b/spec/fixtures/vcr_cassettes/providers_openrouter_parse_error_with_openrouter_openai_o3-mini_raises_detailed_error.yml
new file mode 100644
index 000000000..6acc84a86
--- /dev/null
+++ b/spec/fixtures/vcr_cassettes/providers_openrouter_parse_error_with_openrouter_openai_o3-mini_raises_detailed_error.yml
@@ -0,0 +1,61 @@
+---
+http_interactions:
+- request:
+    method: post
+    uri: https://openrouter.ai/api/v1/chat/completions
+    body:
+      encoding: UTF-8
+      string: '{"model":"openai/o3-mini","messages":[{"role":"user","content":"Hello"}],"stream":false}'
+    headers:
+      User-Agent:
+      - Faraday v2.13.1
+      Authorization:
+      - Bearer sk-or-v1-mocked-key
+      Content-Type:
+      - application/json
+      Accept-Encoding:
+      - gzip;q=1.0,deflate;q=0.6,identity;q=0.3
+      Accept:
+      - "*/*"
+  response:
+    status:
+      code: 403
+      message: Forbidden
+    headers:
+      Date:
+      - Sun, 28 Sep 2025 03:38:43 GMT
+      Content-Type:
+      - application/json
+      Transfer-Encoding:
+      - chunked
+      Connection:
+      - keep-alive
+      Cf-Ray:
+      - "<CF_RAY>"
+      Cf-Cache-Status:
+      - DYNAMIC
+      Access-Control-Allow-Origin:
+      - "*"
+      Vary:
+      - Accept-Encoding
+      Permissions-Policy:
+      - payment=(self "https://checkout.stripe.com" "https://connect-js.stripe.com"
+        "https://js.stripe.com" "https://*.js.stripe.com" "https://hooks.stripe.com")
+      - payment=(self "https://checkout.stripe.com" "https://connect-js.stripe.com"
+        "https://js.stripe.com" "https://*.js.stripe.com" "https://hooks.stripe.com")
+      Referrer-Policy:
+      - no-referrer, strict-origin-when-cross-origin
+      - no-referrer, strict-origin-when-cross-origin
+      X-Cloud-Trace-Context:
+      - dd540491e0534821af69fdd9d8a36c52
+      X-Content-Type-Options:
+      - nosniff
+      - nosniff
+      Server:
+      - cloudflare
+    body:
+      encoding: ASCII-8BIT
+      string: '{"error":{"message":"Provider returned error","code":403,"metadata":{"raw":"{\"error\":{\"code\":\"unsupported_country_region_territory\",\"message\":\"Country,
+        region, or territory not supported\",\"param\":null,\"type\":\"request_forbidden\"}}","provider_name":"OpenAI"}},"user_id":"user_mocked_a"}'
+  recorded_at: Sun, 28 Sep 2025 03:38:43 GMT
+recorded_with: VCR 6.3.1
diff --git a/spec/ruby_llm/providers/openrouter/parse_error_spec.rb b/spec/ruby_llm/providers/openrouter/parse_error_spec.rb
new file mode 100644
index 000000000..aacaa10eb
--- /dev/null
+++ b/spec/ruby_llm/providers/openrouter/parse_error_spec.rb
@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe RubyLLM::Providers::OpenRouter do # rubocop:disable RSpec/SpecFilePathFormat
+  describe '#parse_error' do
+    model = 'openai/o3-mini'
+    provider = 'openrouter'
+    context "with #{provider}/#{model}" do
+      let(:chat) { RubyLLM.chat(model: model, provider: provider) }
+
+      before do
+        RubyLLM.config.openrouter_api_key = 'sk-or-v1-sk-or-v1-mocked-key'
+      end
+
+      it 'raises detailed error' do
+        expect { chat.ask('Hello') }.to raise_error do |error|
+          expect(error).to be_a(RubyLLM::Error)
+          expect(error.message).to eq 'Provider returned error - Country, region, or territory not supported'
+        end
+      end
+    end
+  end
+end