diff --git a/src/NppJsonViewer/Define.h b/src/NppJsonViewer/Define.h
index 5ee80f1..3834ddb 100644
--- a/src/NppJsonViewer/Define.h
+++ b/src/NppJsonViewer/Define.h
@@ -1,4 +1,6 @@
 #pragma once
+#include <string>
+
 #include "PluginInterface.h"
 
 // Define the number of plugin commands here
@@ -64,6 +66,7 @@ const TCHAR STR_INI_FORMATTING_INDENTCOUNT[] = TEXT("INDENTATION_COUNT");
 
 const TCHAR STR_INI_OTHER_SEC[]               = TEXT("Others");
 const TCHAR STR_INI_OTHER_FOLLOW_TAB[]        = TEXT("FOLLOW_TAB");
+const TCHAR STR_INI_OTHER_TREE_ZOOM[]         = TEXT("TREE_ZOOM");
 const TCHAR STR_INI_OTHER_AUTO_FORMAT[]       = TEXT("AUTO_FORMAT");
 const TCHAR STR_INI_OTHER_USE_HIGHLIGHT[]     = TEXT("USE_JSON_HIGHLIGHT");
 const TCHAR STR_INI_OTHER_IGNORE_COMMENT[]    = TEXT("IGNORE_COMMENT");
@@ -117,4 +120,7 @@ struct Setting
     bool         bAutoFormat       = false;
     bool         bUseJsonHighlight = true;
     ParseOptions parseOptions {};
+    int          nTreeZoom         = 100;    // Tree view font zoom in percent (80..250)
+
+    std::wstring configPath;    // Full path of JSONViewer.ini (not persisted)
 };
diff --git a/src/NppJsonViewer/JsonViewDlg.cpp b/src/NppJsonViewer/JsonViewDlg.cpp
index 4080af0..331d2d4 100644
--- a/src/NppJsonViewer/JsonViewDlg.cpp
+++ b/src/NppJsonViewer/JsonViewDlg.cpp
@@ -936,6 +936,19 @@ void JsonViewDlg::UpdateUIOnZoom(int zoomPercentage) const
     SetTreeViewZoom(zoomFactor);
 }
 
+void JsonViewDlg::PersistZoom(int zoomPercentage)
+{
+    const auto& zoomRange = m_pTreeViewZoom->GetRange();
+    if (zoomPercentage < zoomRange.m_nMinZoom || zoomPercentage > zoomRange.m_nMaxZoom)
+        return;
+
+    if (m_pSetting->nTreeZoom != zoomPercentage)
+    {
+        m_pSetting->nTreeZoom = zoomPercentage;
+        ProfileSetting(m_pSetting->configPath).SetSettings(*m_pSetting);
+    }
+}
+
 void JsonViewDlg::HandleZoomOnScroll(WPARAM wParam) const
 {
     int pos   = GetZoomLevel();    // Current zoom level
@@ -1101,6 +1114,10 @@ INT_PTR JsonViewDlg::run_dlgProc(UINT message, WPARAM wParam, LPARAM lParam)
         m_pTreeView->OnInit(getHSelf(), IDC_TREE);
         m_pTreeViewZoom->OnInit(getHSelf(), IDC_ZOOM_SLIDER, IDC_ZOOM_PERCENT);
 
+        // Apply the zoom level restored from JSONViewer.ini
+        const auto& zoomRange = m_pTreeViewZoom->GetRange();
+        UpdateUIOnZoom(std::clamp(m_pSetting->nTreeZoom, zoomRange.m_nMinZoom, zoomRange.m_nMaxZoom));
+
         PrepareButtons();
 
         // Set default node path as JSON
@@ -1182,6 +1199,7 @@ INT_PTR JsonViewDlg::run_dlgProc(UINT message, WPARAM wParam, LPARAM lParam)
         if (GetKeyState(VK_CONTROL) & 0x8000)
         {
             HandleZoomOnScroll(wParam);
+            PersistZoom(GetZoomLevel());
             return TRUE;
         }
         return FALSE;
@@ -1193,9 +1211,18 @@ INT_PTR JsonViewDlg::run_dlgProc(UINT message, WPARAM wParam, LPARAM lParam)
 
         if (reinterpret_cast<HWND>(lParam) == hSlider)
         {
+            // While the thumb is being dragged (TB_THUMBTRACK) the position
+            // changes continuously, so only persist once the gesture is over.
+            // WM_HSCROLL carries the notification code in LOWORD(wParam);
+            // HIWORD is the thumb position itself.
+            const bool bDragging = (LOWORD(wParam) == TB_THUMBTRACK);
+
             int pos = m_pTreeViewZoom->GetPosition();
             UpdateUIOnZoom(pos);
 
+            if (!bDragging)
+                PersistZoom(pos);
+
             return TRUE;
         }
         return FALSE;
diff --git a/src/NppJsonViewer/JsonViewDlg.h b/src/NppJsonViewer/JsonViewDlg.h
index 00cc599..605db34 100644
--- a/src/NppJsonViewer/JsonViewDlg.h
+++ b/src/NppJsonViewer/JsonViewDlg.h
@@ -95,6 +95,7 @@ class JsonViewDlg
     void SetTreeViewZoom(double dwZoomFactor) const;
     void UpdateUIOnZoom(int zoomPercentage) const;
     void HandleZoomOnScroll(WPARAM wParam) const;
+    void PersistZoom(int zoomPercentage);
 
     void HandleTreeEvents(LPARAM lParam) const;
 
diff --git a/src/NppJsonViewer/NppJsonPlugin.cpp b/src/NppJsonViewer/NppJsonPlugin.cpp
index f251481..e7224ff 100644
--- a/src/NppJsonViewer/NppJsonPlugin.cpp
+++ b/src/NppJsonViewer/NppJsonPlugin.cpp
@@ -169,7 +169,8 @@ void NppJsonPlugin::ConstructSetting()
 {
     if (!m_pSetting)
     {
-        m_pSetting = std::make_shared<Setting>();
+        m_pSetting             = std::make_shared<Setting>();
+        m_pSetting->configPath = m_configPath;
         ProfileSetting(m_configPath).GetSettings(*m_pSetting);
     }
 }
diff --git a/src/NppJsonViewer/Profile.cpp b/src/NppJsonViewer/Profile.cpp
index 7f13a18..cf6c9c6 100644
--- a/src/NppJsonViewer/Profile.cpp
+++ b/src/NppJsonViewer/Profile.cpp
@@ -94,6 +94,10 @@ bool ProfileSetting::GetSettings(Setting& info) const
     if (bRetVal)
         info.bFollowCurrentTab = static_cast<bool>(nVal);
 
+    bRetVal = bRetVal && ReadValue(STR_INI_OTHER_SEC, STR_INI_OTHER_TREE_ZOOM, nVal, info.nTreeZoom);
+    if (bRetVal)
+        info.nTreeZoom = nVal;
+
     bRetVal = bRetVal && ReadValue(STR_INI_OTHER_SEC, STR_INI_OTHER_AUTO_FORMAT, nVal, info.bAutoFormat);
     if (bRetVal)
         info.bAutoFormat = static_cast<bool>(nVal);
@@ -127,6 +131,7 @@ bool ProfileSetting::SetSettings(const Setting& info) const
     bRetVal = bRetVal && WriteValue(STR_INI_FORMATTING_SEC, STR_INI_FORMATTING_INDENTCOUNT, info.indent.len);
 
     bRetVal = bRetVal && WriteValue(STR_INI_OTHER_SEC, STR_INI_OTHER_FOLLOW_TAB, info.bFollowCurrentTab);
+    bRetVal = bRetVal && WriteValue(STR_INI_OTHER_SEC, STR_INI_OTHER_TREE_ZOOM, info.nTreeZoom);
     bRetVal = bRetVal && WriteValue(STR_INI_OTHER_SEC, STR_INI_OTHER_AUTO_FORMAT, info.bAutoFormat);
     bRetVal = bRetVal && WriteValue(STR_INI_OTHER_SEC, STR_INI_OTHER_USE_HIGHLIGHT, info.bUseJsonHighlight);
     bRetVal = bRetVal && WriteValue(STR_INI_OTHER_SEC, STR_INI_OTHER_IGNORE_COMMENT, info.parseOptions.bIgnoreComment);
diff --git a/tests/UnitTest/ProfileTest.cpp b/tests/UnitTest/ProfileTest.cpp
index 10ab846..873d9f6 100644
--- a/tests/UnitTest/ProfileTest.cpp
+++ b/tests/UnitTest/ProfileTest.cpp
@@ -137,6 +137,7 @@ namespace ProfileSettingTests
         EXPECT_EQ(setting.bFollowCurrentTab, false);
         EXPECT_EQ(setting.bAutoFormat, false);
         EXPECT_EQ(setting.bUseJsonHighlight, true);
+        EXPECT_EQ(setting.nTreeZoom, 100);
 
         EXPECT_EQ(setting.parseOptions.bIgnoreComment, true);
         EXPECT_EQ(setting.parseOptions.bIgnoreTrailingComma, true);
@@ -173,9 +174,32 @@ namespace ProfileSettingTests
         EXPECT_EQ(actual.bFollowCurrentTab, expected.bFollowCurrentTab);
         EXPECT_EQ(actual.bAutoFormat, expected.bAutoFormat);
         EXPECT_EQ(actual.bUseJsonHighlight, expected.bUseJsonHighlight);
+        EXPECT_EQ(actual.nTreeZoom, expected.nTreeZoom);
 
         EXPECT_EQ(actual.parseOptions.bIgnoreComment, expected.parseOptions.bIgnoreComment);
         EXPECT_EQ(actual.parseOptions.bIgnoreTrailingComma, expected.parseOptions.bIgnoreTrailingComma);
         EXPECT_EQ(actual.parseOptions.bReplaceUndefined, expected.parseOptions.bReplaceUndefined);
     }
+
+    TEST_F(ProfileTest, TreeZoom_RoundTrip)
+    {
+        // a profile without the TREE_ZOOM key falls back to 100%
+        {
+            Setting setting {};
+            EXPECT_TRUE(m_pProfile->GetSettings(setting));
+            EXPECT_EQ(setting.nTreeZoom, 100);
+        }
+
+        // every value inside the slider range must survive a write/read cycle
+        for (int zoom : { 80, 100, 150, 200, 250 })
+        {
+            Setting expected {};
+            expected.nTreeZoom = zoom;
+            ASSERT_TRUE(m_pProfile->SetSettings(expected)) << zoom;
+
+            Setting actual {};
+            ASSERT_TRUE(m_pProfile->GetSettings(actual)) << zoom;
+            EXPECT_EQ(actual.nTreeZoom, zoom);
+        }
+    }
 }    // namespace ProfileSettingTests