You need to enroll Apple developer program to submit the application to the mac app store. You need to get the certificate from Apple to sign your app. First, you need to add the team id to the info.plist file. Add the following code into it:

<plist version="1.0">
  <dict>
    ...
    <key>ElectronTeamID</key>
    <string>TEAM_ID</string>
  </dict>
</plist>

Then, prepare the following file with the content:

child.plist:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
  <dict>
    <key>com.apple.security.app-sandbox</key>
    <true/>
    <key>com.apple.security.inherit</key>
    <true/>
  </dict>
</plist>

parent.plist:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
  <dict>
    <key>com.apple.security.app-sandbox</key>
    <true/>
    <key>com.apple.security.application-groups</key>
    <string>TEAM_ID.your.bundle.id</string>
  </dict>
</plist>

You have to replace TEAM_ID with your team ID, and replace your.bundle.id with the bundle ID of your app.

Then, sign your app with the following script:

#!/bin/bash

# Name of your app.
APP="YourApp"
# The path of your app to sign.
APP_PATH="/path/to/YourApp.app"
# The path to the location you want to put the signed package.
RESULT_PATH="~/Desktop/$APP.pkg"
# The name of certificates you requested.
APP_KEY="3rd Party Mac Developer Application: Company Name (APPIDENTITY)"
INSTALLER_KEY="3rd Party Mac Developer Installer: Company Name (APPIDENTITY)"
# The path of your plist files.
CHILD_PLIST="/path/to/child.plist"
PARENT_PLIST="/path/to/parent.plist"

FRAMEWORKS_PATH="$APP_PATH/Contents/Frameworks"

codesign -s "$APP_KEY" -f --entitlements "$CHILD_PLIST" "$FRAMEWORKS_PATH/Electron Framework.framework/Versions/A/Electron Framework"
codesign -s "$APP_KEY" -f --entitlements "$CHILD_PLIST" "$FRAMEWORKS_PATH/Electron Framework.framework/Versions/A/Libraries/libffmpeg.dylib"
codesign -s "$APP_KEY" -f --entitlements "$CHILD_PLIST" "$FRAMEWORKS_PATH/Electron Framework.framework/Versions/A/Libraries/libnode.dylib"
codesign -s "$APP_KEY" -f --entitlements "$CHILD_PLIST" "$FRAMEWORKS_PATH/Electron Framework.framework"
codesign -s "$APP_KEY" -f --entitlements "$CHILD_PLIST" "$FRAMEWORKS_PATH/$APP Helper.app/Contents/MacOS/$APP Helper"
codesign -s "$APP_KEY" -f --entitlements "$CHILD_PLIST" "$FRAMEWORKS_PATH/$APP Helper.app/"
codesign -s "$APP_KEY" -f --entitlements "$CHILD_PLIST" "$FRAMEWORKS_PATH/$APP Helper EH.app/Contents/MacOS/$APP Helper EH"
codesign -s "$APP_KEY" -f --entitlements "$CHILD_PLIST" "$FRAMEWORKS_PATH/$APP Helper EH.app/"
codesign -s "$APP_KEY" -f --entitlements "$CHILD_PLIST" "$FRAMEWORKS_PATH/$APP Helper NP.app/Contents/MacOS/$APP Helper NP"
codesign -s "$APP_KEY" -f --entitlements "$CHILD_PLIST" "$FRAMEWORKS_PATH/$APP Helper NP.app/"
codesign -s "$APP_KEY" -f --entitlements "$CHILD_PLIST" "$APP_PATH/Contents/MacOS/$APP"
codesign -s "$APP_KEY" -f --entitlements "$PARENT_PLIST" "$APP_PATH"

productbuild --component "$APP_PATH" /Applications --sign "$INSTALLER_KEY" "$RESULT_PATH"

Native modules used in your app also need to be signed. If you are using electron-osx-sign, ensure that you include the path to the built binaries in the argument list:

electron-osx-sign YourApp.app YourApp.app/Contents/Resources/app/node_modules/nativemodule/build/release/nativemodule

After these steps, you can upload your application and request for approval through the Apple store.