diff --git a/.github/workflows/app-ci.yml b/.github/workflows/app-ci.yml
index bbfcdbe..bc6edc5 100644
--- a/.github/workflows/app-ci.yml
+++ b/.github/workflows/app-ci.yml
@@ -36,6 +36,25 @@ jobs:
       - name: Run Android quality checks
         run: ./gradlew ktlintCheck detekt testDebugUnitTest assembleDebug assembleRelease --stacktrace
 
+      - name: Verify debug APK signature
+        shell: bash
+        run: |
+          set -euo pipefail
+          apksigner_bin="$(find "${ANDROID_HOME}/build-tools" -maxdepth 2 -type f -name apksigner | sort -V | tail -n1)"
+          if [[ -z "${apksigner_bin}" ]]; then
+            echo "apksigner not found under ${ANDROID_HOME}/build-tools" >&2
+            exit 1
+          fi
+          shopt -s nullglob
+          apks=(app/build/outputs/apk/debug/*.apk)
+          if (( ${#apks[@]} == 0 )); then
+            echo "No debug APKs found" >&2
+            exit 1
+          fi
+          for apk in "${apks[@]}"; do
+            "${apksigner_bin}" verify --verbose --print-certs "$apk"
+          done
+
       - name: Upload debug APK
         uses: actions/upload-artifact@v6
         with:
diff --git a/.github/workflows/app-release.yml b/.github/workflows/app-release.yml
index 1aefc2d..6e44953 100644
--- a/.github/workflows/app-release.yml
+++ b/.github/workflows/app-release.yml
@@ -26,9 +26,56 @@ jobs:
       - name: Setup Android SDK
         uses: android-actions/setup-android@v3
 
+      - name: Decode release keystore
+        shell: bash
+        env:
+          AUTOFISH_RELEASE_KEYSTORE_BASE64: ${{ secrets.AUTOFISH_RELEASE_KEYSTORE_BASE64 }}
+          AUTOFISH_RELEASE_STORE_PASSWORD: ${{ secrets.AUTOFISH_RELEASE_STORE_PASSWORD }}
+          AUTOFISH_RELEASE_KEY_ALIAS: ${{ secrets.AUTOFISH_RELEASE_KEY_ALIAS }}
+          AUTOFISH_RELEASE_KEY_PASSWORD: ${{ secrets.AUTOFISH_RELEASE_KEY_PASSWORD }}
+        run: |
+          set -euo pipefail
+          for secret_name in \
+            AUTOFISH_RELEASE_KEYSTORE_BASE64 \
+            AUTOFISH_RELEASE_STORE_PASSWORD \
+            AUTOFISH_RELEASE_KEY_ALIAS \
+            AUTOFISH_RELEASE_KEY_PASSWORD
+          do
+            if [[ -z "${!secret_name}" ]]; then
+              echo "$secret_name is required for app releases" >&2
+              exit 1
+            fi
+          done
+          mkdir -p "$RUNNER_TEMP/autofish-signing"
+          printf '%s' "${AUTOFISH_RELEASE_KEYSTORE_BASE64}" | base64 --decode > "$RUNNER_TEMP/autofish-signing/release.keystore"
+
       - name: Build release APK
+        env:
+          AUTOFISH_RELEASE_STORE_FILE: ${{ runner.temp }}/autofish-signing/release.keystore
+          AUTOFISH_RELEASE_STORE_PASSWORD: ${{ secrets.AUTOFISH_RELEASE_STORE_PASSWORD }}
+          AUTOFISH_RELEASE_KEY_ALIAS: ${{ secrets.AUTOFISH_RELEASE_KEY_ALIAS }}
+          AUTOFISH_RELEASE_KEY_PASSWORD: ${{ secrets.AUTOFISH_RELEASE_KEY_PASSWORD }}
         run: ./gradlew assembleRelease
 
+      - name: Verify release APK signature
+        shell: bash
+        run: |
+          set -euo pipefail
+          apksigner_bin="$(find "${ANDROID_HOME}/build-tools" -maxdepth 2 -type f -name apksigner | sort -V | tail -n1)"
+          if [[ -z "${apksigner_bin}" ]]; then
+            echo "apksigner not found under ${ANDROID_HOME}/build-tools" >&2
+            exit 1
+          fi
+          shopt -s nullglob
+          apks=(app/build/outputs/apk/release/*.apk)
+          if (( ${#apks[@]} == 0 )); then
+            echo "No release APKs found" >&2
+            exit 1
+          fi
+          for apk in "${apks[@]}"; do
+            "${apksigner_bin}" verify --verbose --print-certs "$apk"
+          done
+
       - name: Collect APKs
         shell: bash
         run: |
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 33e9d40..9369fb9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,10 @@ All notable changes to this project will be documented in this file.
 
 ## [Unreleased]
 
+### Fixed
+- Sign app release APKs in the GitHub release workflow and verify release artifacts with `apksigner` before publishing.
+- Verify debug APK signatures in Android CI so installability regressions are caught earlier.
+
 ## [0.5.0] - 2026-05-16
 
 Range: `app-v0.4.0` / `cli-v0.4.0` .. `app-v0.5.0` / `cli-v0.5.0`
diff --git a/app/build.gradle.kts b/app/build.gradle.kts
index bb57c7f..5d61c11 100644
--- a/app/build.gradle.kts
+++ b/app/build.gradle.kts
@@ -48,6 +48,16 @@ val versionCodeProp =
         rawVersionCodeProp!!
     }
 
+val releaseStoreFile = providers.environmentVariable("AUTOFISH_RELEASE_STORE_FILE")
+val releaseStorePassword = providers.environmentVariable("AUTOFISH_RELEASE_STORE_PASSWORD")
+val releaseKeyAlias = providers.environmentVariable("AUTOFISH_RELEASE_KEY_ALIAS")
+val releaseKeyPassword = providers.environmentVariable("AUTOFISH_RELEASE_KEY_PASSWORD")
+val hasReleaseSigningConfig =
+    releaseStoreFile.isPresent &&
+        releaseStorePassword.isPresent &&
+        releaseKeyAlias.isPresent &&
+        releaseKeyPassword.isPresent
+
 android {
     namespace = "com.memohai.autofish"
     compileSdk = 36
@@ -60,6 +70,17 @@ android {
         versionName = versionNameProp
     }
 
+    signingConfigs {
+        if (hasReleaseSigningConfig) {
+            create("release") {
+                storeFile = file(releaseStoreFile.get())
+                storePassword = releaseStorePassword.get()
+                keyAlias = releaseKeyAlias.get()
+                keyPassword = releaseKeyPassword.get()
+            }
+        }
+    }
+
     buildTypes {
         debug {
             applicationIdSuffix = ".debug"
@@ -73,6 +94,9 @@ android {
                 getDefaultProguardFile("proguard-android-optimize.txt"),
                 "proguard-rules.pro",
             )
+            if (hasReleaseSigningConfig) {
+                signingConfig = signingConfigs.getByName("release")
+            }
         }
     }