diff --git a/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/MainActivity.kt b/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/MainActivity.kt
index 59f6fd3..a0f2edf 100644
--- a/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/MainActivity.kt
+++ b/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/MainActivity.kt
@@ -4,18 +4,31 @@ import android.os.Bundle
 import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
+import androidx.compose.runtime.getValue
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import androidx.lifecycle.lifecycleScope
+import com.vaultdrop.mobile.domain.ThemePreferenceStore
 import com.vaultdrop.mobile.ui.navigation.VaultDropApp
 import com.vaultdrop.mobile.ui.theme.VaultDropTheme
 import dagger.hilt.android.AndroidEntryPoint
+import javax.inject.Inject
+import kotlinx.coroutines.launch
 
 @AndroidEntryPoint
 class MainActivity : ComponentActivity() {
 
+    @Inject
+    lateinit var themePreferenceStore: ThemePreferenceStore
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         enableEdgeToEdge()
+
+        lifecycleScope.launch { themePreferenceStore.load() }
+
         setContent {
-            VaultDropTheme {
+            val theme by themePreferenceStore.theme.collectAsStateWithLifecycle()
+            VaultDropTheme(theme = theme) {
                 VaultDropApp()
             }
         }
diff --git a/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/domain/PrefKeys.kt b/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/domain/PrefKeys.kt
index fff660e..795faea 100644
--- a/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/domain/PrefKeys.kt
+++ b/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/domain/PrefKeys.kt
@@ -5,4 +5,5 @@ object PrefKeys {
     const val DEVICE_USER_ID = "device_user_id"
     const val ACTIVE_USER_ID = "active_user_id"
     const val SYNC_MODE = "sync_mode"
+    const val THEME = "theme"
 }
\ No newline at end of file
diff --git a/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/domain/ThemePreference.kt b/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/domain/ThemePreference.kt
new file mode 100644
index 0000000..c6c0156
--- /dev/null
+++ b/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/domain/ThemePreference.kt
@@ -0,0 +1,17 @@
+package com.vaultdrop.mobile.domain
+
+/**
+ * Préférence d'affichage de la page Réglages, persistée dans `user_preferences`.
+ * `SYSTEM` (défaut) = suivre le thème du système ; `LIGHT`/`DARK` = forcer.
+ */
+enum class ThemePreference(val storedValue: String) {
+    SYSTEM("system"),
+    LIGHT("light"),
+    DARK("dark"),
+    ;
+
+    companion object {
+        fun fromStored(value: String?): ThemePreference =
+            entries.firstOrNull { it.storedValue == value } ?: SYSTEM
+    }
+}
\ No newline at end of file
diff --git a/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/domain/ThemePreferenceStore.kt b/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/domain/ThemePreferenceStore.kt
new file mode 100644
index 0000000..c5d3c65
--- /dev/null
+++ b/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/domain/ThemePreferenceStore.kt
@@ -0,0 +1,40 @@
+package com.vaultdrop.mobile.domain
+
+import com.vaultdrop.mobile.data.local.dao.UserPreferenceDao
+import com.vaultdrop.mobile.data.local.entity.UserPreferenceEntity
+import java.util.concurrent.atomic.AtomicBoolean
+import javax.inject.Inject
+import javax.inject.Singleton
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+
+/**
+ * Préférence de thème (clair/sombre) : valeur par défaut SYSTEM, chargée une
+ * fois depuis `user_preferences` puis exposée en [StateFlow]. La source le
+ * thread-safe : écritures et lectures passent par le DAO Room (IO).
+ */
+@Singleton
+class ThemePreferenceStore @Inject constructor(
+    private val userPreferenceDao: UserPreferenceDao,
+) {
+
+    private val loaded = AtomicBoolean(false)
+
+    private val _theme = MutableStateFlow<ThemePreference>(ThemePreference.SYSTEM)
+    val theme: StateFlow<ThemePreference> = _theme.asStateFlow()
+
+    /** Charge la valeur persistée au boot (idempotent). */
+    suspend fun load() {
+        if (!loaded.compareAndSet(false, true)) return
+        val stored = userPreferenceDao.getValue(PrefKeys.THEME)
+        _theme.value = ThemePreference.fromStored(stored)
+    }
+
+    suspend fun set(theme: ThemePreference) {
+        _theme.value = theme
+        userPreferenceDao.upsert(
+            UserPreferenceEntity(PrefKeys.THEME, theme.storedValue, System.currentTimeMillis()),
+        )
+    }
+}
\ No newline at end of file
diff --git a/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/ui/settings/SettingsScreen.kt b/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/ui/settings/SettingsScreen.kt
index e063c46..472af8f 100644
--- a/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/ui/settings/SettingsScreen.kt
+++ b/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/ui/settings/SettingsScreen.kt
@@ -1,17 +1,31 @@
 package com.vaultdrop.mobile.ui.settings
 
-import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.isSystemInDarkTheme
+import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.DarkMode
 import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.HorizontalDivider
+import androidx.compose.material3.Icon
+import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Switch
 import androidx.compose.material3.Text
 import androidx.compose.material3.TopAppBar
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.res.stringResource
-import androidx.compose.ui.text.style.TextAlign
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.dp
+import androidx.hilt.navigation.compose.hiltViewModel
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import com.vaultdrop.mobile.R
+import com.vaultdrop.mobile.domain.ThemePreference
 import com.vaultdrop.mobile.ui.navigation.FloatingNavBar
 import com.vaultdrop.mobile.ui.navigation.NavTab
 
@@ -20,7 +34,15 @@ import com.vaultdrop.mobile.ui.navigation.NavTab
 fun SettingsScreen(
     selectedTab: NavTab,
     onTabSelected: (NavTab) -> Unit,
+    viewModel: SettingsViewModel = hiltViewModel(),
 ) {
+    val theme by viewModel.theme.collectAsStateWithLifecycle()
+    val darkNow = when (theme) {
+        ThemePreference.DARK -> true
+        ThemePreference.LIGHT -> false
+        ThemePreference.SYSTEM -> isSystemInDarkTheme()
+    }
+
     Scaffold(
         topBar = {
             TopAppBar(title = { Text(stringResource(R.string.settings)) })
@@ -29,14 +51,62 @@ fun SettingsScreen(
             FloatingNavBar(selected = selectedTab, onSelect = onTabSelected)
         },
     ) { padding ->
-        Box(
-            modifier = Modifier.fillMaxSize(),
-            contentAlignment = Alignment.Center,
+        Column(
+            modifier = Modifier
+                .fillMaxSize()
+                .padding(padding),
         ) {
-            Text(
-                text = stringResource(R.string.settings),
-                textAlign = TextAlign.Center,
+            HorizontalDivider()
+            SettingsRow(
+                icon = { Icon(Icons.Filled.DarkMode, contentDescription = null) },
+                title = stringResource(R.string.settings_dark_mode),
+                subtitle = stringResource(
+                    if (darkNow) R.string.settings_dark_mode_on
+                    else R.string.settings_dark_mode_off,
+                ),
+                trailing = {
+                    Switch(
+                        checked = darkNow,
+                        onCheckedChange = { on ->
+                            viewModel.setTheme(if (on) ThemePreference.DARK else ThemePreference.LIGHT)
+                        },
+                    )
+                },
             )
         }
     }
 }
+
+@Composable
+private fun SettingsRow(
+    icon: @Composable () -> Unit,
+    title: String,
+    subtitle: String,
+    trailing: @Composable () -> Unit,
+) {
+    androidx.compose.foundation.layout.Row(
+        modifier = Modifier
+            .fillMaxWidth()
+            .padding(16.dp),
+        verticalAlignment = Alignment.CenterVertically,
+    ) {
+        icon()
+        Column(
+            modifier = Modifier
+                .weight(1f)
+                .padding(horizontal = 16.dp),
+        ) {
+            Text(
+                text = title,
+                style = MaterialTheme.typography.bodyLarge,
+                fontWeight = FontWeight.Medium,
+            )
+            Text(
+                text = subtitle,
+                style = MaterialTheme.typography.bodySmall,
+                color = MaterialTheme.colorScheme.onSurfaceVariant,
+            )
+        }
+        trailing()
+    }
+}
\ No newline at end of file
diff --git a/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/ui/settings/SettingsViewModel.kt b/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/ui/settings/SettingsViewModel.kt
new file mode 100644
index 0000000..1a4a52c
--- /dev/null
+++ b/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/ui/settings/SettingsViewModel.kt
@@ -0,0 +1,26 @@
+package com.vaultdrop.mobile.ui.settings
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import com.vaultdrop.mobile.domain.ThemePreference
+import com.vaultdrop.mobile.domain.ThemePreferenceStore
+import dagger.hilt.android.lifecycle.HiltViewModel
+import javax.inject.Inject
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.launch
+
+@HiltViewModel
+class SettingsViewModel @Inject constructor(
+    private val themePreferenceStore: ThemePreferenceStore,
+) : ViewModel() {
+
+    val theme: StateFlow<ThemePreference> = themePreferenceStore.theme
+
+    init {
+        viewModelScope.launch { themePreferenceStore.load() }
+    }
+
+    fun setTheme(theme: ThemePreference) {
+        viewModelScope.launch { themePreferenceStore.set(theme) }
+    }
+}
\ No newline at end of file
diff --git a/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/ui/theme/Theme.kt b/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/ui/theme/Theme.kt
index 6cd0c1f..d0a36a2 100644
--- a/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/ui/theme/Theme.kt
+++ b/mobile-kotlin/app/src/main/java/com/vaultdrop/mobile/ui/theme/Theme.kt
@@ -4,6 +4,7 @@ import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.darkColorScheme
 import androidx.compose.material3.lightColorScheme
 import androidx.compose.runtime.Composable
+import com.vaultdrop.mobile.domain.ThemePreference
 
 private val LightColors = lightColorScheme(
     primary = BrandBlue,
@@ -17,6 +18,19 @@ private val DarkColors = darkColorScheme(
     onPrimary = androidx.compose.ui.graphics.Color.Black,
 )
 
+@Composable
+fun VaultDropTheme(
+    theme: ThemePreference,
+    content: @Composable () -> Unit,
+) {
+    val darkTheme = when (theme) {
+        ThemePreference.DARK -> true
+        ThemePreference.LIGHT -> false
+        ThemePreference.SYSTEM -> isSystemInDarkTheme()
+    }
+    VaultDropTheme(darkTheme = darkTheme, content = content)
+}
+
 @Composable
 fun VaultDropTheme(
     darkTheme: Boolean = isSystemInDarkTheme(),
diff --git a/mobile-kotlin/app/src/main/res/values-en/strings.xml b/mobile-kotlin/app/src/main/res/values-en/strings.xml
index 22ab478..fc96623 100644
--- a/mobile-kotlin/app/src/main/res/values-en/strings.xml
+++ b/mobile-kotlin/app/src/main/res/values-en/strings.xml
@@ -27,6 +27,9 @@
     <string name="nav_search">Search</string>
     <string name="nav_settings">Settings</string>
     <string name="settings">Settings</string>
+    <string name="settings_dark_mode">Dark mode</string>
+    <string name="settings_dark_mode_on">Dark theme active</string>
+    <string name="settings_dark_mode_off">Light theme active</string>
 
     <!-- Search -->
     <string name="search">Search</string>
diff --git a/mobile-kotlin/app/src/main/res/values/strings.xml b/mobile-kotlin/app/src/main/res/values/strings.xml
index 0412064..f824cff 100644
--- a/mobile-kotlin/app/src/main/res/values/strings.xml
+++ b/mobile-kotlin/app/src/main/res/values/strings.xml
@@ -28,6 +28,9 @@
     <string name="nav_search">Recherche</string>
     <string name="nav_settings">Réglages</string>
     <string name="settings">Réglages</string>
+    <string name="settings_dark_mode">Mode sombre</string>
+    <string name="settings_dark_mode_on">Thème sombre actif</string>
+    <string name="settings_dark_mode_off">Thème clair actif</string>
 
     <!-- Recherche -->
     <string name="search">Recherche</string>