diff --git a/README.md b/README.md
index e51bfb7..9edf487 100644
--- a/README.md
+++ b/README.md
@@ -127,10 +127,14 @@ prism-tui stores its settings in a TOML config file:
 ```toml
 default_sort = "Last Played"
 sort_ascending = true
-data_dir = "~/Games/PrismLauncher"  # optional, overrides auto-detection
+data_dir = "~/Games/PrismLauncher"          # optional, overrides auto-detection
+instances_dir = "/mnt/ssd/mc-instances"     # optional, overrides instances path
 ```
 
-Sort and sort-direction preferences are saved automatically. The `data_dir` option supports `~` tilde expansion.
+Sort and sort-direction preferences are saved automatically. Both `data_dir` and `instances_dir` support `~` tilde expansion.
+
+- `data_dir` overrides the root PrismLauncher directory (affects accounts, logs, launcher config, and instances).
+- `instances_dir` overrides only the instances path, useful when instances live on a separate drive or non-standard location. When unset, defaults to `<data_dir>/instances`.
 
 ## Architecture
 
diff --git a/src/data/app_config.rs b/src/data/app_config.rs
index ddca2c5..827cebf 100644
--- a/src/data/app_config.rs
+++ b/src/data/app_config.rs
@@ -11,6 +11,8 @@ pub struct AppConfig {
     pub sort_ascending: bool,
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub data_dir: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub instances_dir: Option<String>,
 }
 
 fn default_true() -> bool {
@@ -27,6 +29,7 @@ impl Default for AppConfig {
             default_sort: default_sort(),
             sort_ascending: true,
             data_dir: None,
+            instances_dir: None,
         }
     }
 }
@@ -72,6 +75,10 @@ impl AppConfig {
         self.data_dir.as_ref().map(|p| expand_tilde(p))
     }
 
+    pub fn resolved_instances_dir(&self) -> Option<PathBuf> {
+        self.instances_dir.as_ref().map(|p| expand_tilde(p))
+    }
+
     pub fn default_sort_mode(&self) -> SortMode {
         match self.default_sort.as_str() {
             "Name" => SortMode::Name,
diff --git a/src/data/config.rs b/src/data/config.rs
index a6951e0..dfc2477 100644
--- a/src/data/config.rs
+++ b/src/data/config.rs
@@ -5,12 +5,22 @@ use std::path::{Path, PathBuf};
 
 pub struct PrismConfig {
     pub data_dir: PathBuf,
+    instances_dir_override: Option<PathBuf>,
     #[allow(dead_code)]
     pub selected_instance: Option<String>,
 }
 
 impl PrismConfig {
-    pub fn load(data_dir: &Path) -> Result<Self> {
+    pub fn load(data_dir: &Path, instances_dir_override: Option<PathBuf>) -> Result<Self> {
+        if let Some(ref dir) = instances_dir_override
+            && !dir.exists()
+        {
+            return Err(PrismError::Config(format!(
+                "Configured instances_dir does not exist: {}",
+                dir.display()
+            )));
+        }
+
         let config_path = data_dir.join("prismlauncher.cfg");
         let mut config = Ini::new();
 
@@ -25,12 +35,17 @@ impl PrismConfig {
 
         Ok(Self {
             data_dir: data_dir.to_path_buf(),
+            instances_dir_override,
             selected_instance,
         })
     }
 
     pub fn instances_dir(&self) -> PathBuf {
-        self.data_dir.join("instances")
+        if let Some(ref dir) = self.instances_dir_override {
+            dir.clone()
+        } else {
+            self.data_dir.join("instances")
+        }
     }
 
     pub fn accounts_path(&self) -> PathBuf {
diff --git a/src/main.rs b/src/main.rs
index a9bf142..4c50e20 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -21,7 +21,7 @@ async fn main() -> Result<()> {
 
     let app_config = AppConfig::load();
     let data_dir = find_prism_data_dir(app_config.resolved_data_dir())?;
-    let config = PrismConfig::load(&data_dir)?;
+    let config = PrismConfig::load(&data_dir, app_config.resolved_instances_dir())?;
     let mut app = App::new(config, app_config)?;
     let mut terminal = Terminal::new()?;
     let mut events = EventStream::new(Duration::from_millis(250));