diff --git a/app/models/theme_setting.rb b/app/models/theme_setting.rb
index d6698746711..e97ac20a373 100644
--- a/app/models/theme_setting.rb
+++ b/app/models/theme_setting.rb
@@ -8,9 +8,12 @@ class ThemeSetting < ActiveRecord::Base
   TYPES_ENUM =
     Enum.new(integer: 0, float: 1, string: 2, bool: 3, list: 4, enum: 5, upload: 6, objects: 7)
 
+  MAXIMUM_JSON_VALUE_SIZE_BYTES = 0.5 * 1024 * 1024 # 0.5 MB
+
   validates_presence_of :name, :theme
   before_validation :objects_type_enabled
   validates :data_type, inclusion: { in: TYPES_ENUM.values }
+  validate :json_value_size, if: -> { self.data_type == TYPES_ENUM[:objects] }
   validates :name, length: { maximum: 255 }
 
   after_save :clear_settings_cache
@@ -52,6 +55,18 @@ class ThemeSetting < ActiveRecord::Base
       self.data_type = nil
     end
   end
+
+  def json_value_size
+    if json_value.to_json.size > MAXIMUM_JSON_VALUE_SIZE_BYTES
+      errors.add(
+        :json_value,
+        I18n.t(
+          "theme_settings.errors.json_value.too_large",
+          max_size_megabytes: MAXIMUM_JSON_VALUE_SIZE_BYTES / 1024 / 1024,
+        ),
+      )
+    end
+  end
 end
 
 # == Schema Information
diff --git a/config/locales/server.en.yml b/config/locales/server.en.yml
index 0eb40fc5f3c..45360ffed0f 100644
--- a/config/locales/server.en.yml
+++ b/config/locales/server.en.yml
@@ -74,6 +74,10 @@ en:
     enabled_filter: "Enabled"
     disabled_filter: "Disabled"
     updates_available_filter: "Updates Available"
+  theme_settings:
+    errors:
+      json_value:
+        too_large: "has exceeded the maximum size of %{max_size} bytes."
   themes:
     bad_color_scheme: "Can not update theme, invalid color palette"
     other_error: "Something went wrong updating theme"
diff --git a/spec/models/theme_setting_spec.rb b/spec/models/theme_setting_spec.rb
index 1bb52a558e9..64cdc4f8b9b 100644
--- a/spec/models/theme_setting_spec.rb
+++ b/spec/models/theme_setting_spec.rb
@@ -22,5 +22,33 @@ RSpec.describe ThemeSetting do
 
       expect(theme_setting.valid?).to eq(true)
     end
+
+    it "should be invalid when json_value size is greater than the maximum allowed size" do
+      SiteSetting.experimental_objects_type_for_theme_settings = true
+
+      json_value = { "key" => "value" }
+      bytesize = json_value.to_json.bytesize
+
+      expect(bytesize).to eq(15)
+
+      stub_const(ThemeSetting, "MAXIMUM_JSON_VALUE_SIZE_BYTES", bytesize - 1) do
+        theme_setting =
+          ThemeSetting.new(
+            name: "test",
+            data_type: ThemeSetting.types[:objects],
+            theme:,
+            json_value:,
+          )
+
+        expect(theme_setting.valid?).to eq(false)
+
+        expect(theme_setting.errors[:json_value]).to contain_exactly(
+          I18n.t(
+            "theme_settings.errors.json_value.too_large",
+            max_size_megabytes: (bytesize - 1) / 1024 / 1024,
+          ),
+        )
+      end
+    end
   end
 end