diff --git a/packages/hadron-build/lib/mac-notary-service.js b/packages/hadron-build/lib/mac-notary-service.js
new file mode 100644
index 00000000000..d45d0bb4464
--- /dev/null
+++ b/packages/hadron-build/lib/mac-notary-service.js
@@ -0,0 +1,90 @@
+// eslint-disable-next-line strict
+'use strict';
+const download = require('download');
+const path = require('path');
+const { promises: fs } = require('fs');
+const debug = require('debug')('hadron-build:macos-notarization');
+const { promisify } = require('util');
+const childProcess = require('child_process');
+const execFile = promisify(childProcess.execFile);
+
+async function setupMacosNotary() {
+  try {
+    await fs.access('macnotary/macnotary');
+    debug('macnotary already downloaded');
+  } catch (err) {
+    debug('downloading macnotary');
+    await download(process.env.MACOS_NOTARY_CLIENT_URL, 'macnotary', {
+      extract: true,
+      strip: 1 // remove leading platform + arch directory
+    });
+    await fs.chmod('macnotary/macnotary', 0o755); // ensure +x is set
+  }
+}
+
+/**
+ * Notarize a resource with the macOS notary service.
+ * https://wiki.corp.mongodb.com/display/BUILD/How+to+use+MacOS+notary+service
+ *
+ * Notarization is a three step process:
+ * 1. All the files to be notarized are zipped up into a single file.
+ * 2. The zip file is uploaded to the notary service. It signs all the
+ *   files in the zip file and returns a new zip file with the signed files.
+ * 3. The orginal files are removed and the signed files are unzipped into
+ *  their place.
+ *
+ * @param {string} src The path to the resource to notarize. It can be a directory or a file.
+ * @param {object} notarizeOptions
+ * @param {string} notarizeOptions.bundleId
+ * @param {string} [notarizeOptions.macosEntitlements]
+ */
+async function notarize(src, notarizeOptions) {
+  debug(`Signing and notarizing "${src}"`);
+
+  await setupMacosNotary();
+
+  const fileName = path.basename(src);
+  const unsignedArchive = `${fileName}.zip`;
+  const signedArchive = `${fileName}.signed.zip`;
+
+  const execOpts = {
+    cwd: path.dirname(src),
+    encoding: 'utf8',
+  };
+
+  // Step:1 - zip up the file/folder to unsignedArchive
+  debug(`running "zip -y -r '${unsignedArchive}' '${fileName}'"`);
+  await execFile('zip', ['-y', '-r', unsignedArchive, fileName], execOpts);
+
+  try {
+    // Step:2 - send the zip to notary service and save the result to signedArchive
+    debug(`sending file to notary service (bundle id = ${notarizeOptions.bundleId})`);
+    const macnotaryResult = await execFile(path.resolve('macnotary/macnotary'), [
+      '-t', 'app',
+      '-m', 'notarizeAndSign',
+      '-u', process.env.MACOS_NOTARY_API_URL,
+      '-b', notarizeOptions.bundleId,
+      '-f', unsignedArchive,
+      '-o', signedArchive,
+      '--verify',
+      ...(notarizeOptions.macosEntitlements ? ['-e', notarizeOptions.macosEntitlements] : [])
+    ], execOpts);
+    debug('macnotary result:', macnotaryResult.stdout, macnotaryResult.stderr);
+    debug('ls', (await execFile('ls', ['-lh'], execOpts)).stdout);
+
+    // Step:3 - remove existing src, unzip signedArchive to src
+    debug('removing existing directory contents');
+    await execFile('rm', ['-r', fileName], execOpts);
+    debug(`unzipping with "unzip -u ${signedArchive}"`);
+    await execFile('unzip', ['-u', signedArchive], execOpts);
+  } finally {
+    // cleanup - remove signedArchive and unsignedArchive
+    debug('ls', (await execFile('ls', ['-lh'], execOpts)).stdout);
+    debug(`removing ${signedArchive} and ${unsignedArchive}`);
+    await execFile('rm', ['-r', signedArchive, unsignedArchive], execOpts).catch(err => {
+      debug('error cleaning up', err);
+    });
+  }
+}
+
+module.exports = { notarize };
diff --git a/packages/hadron-build/lib/target.js b/packages/hadron-build/lib/target.js
index 1ec0adff3ca..2ecc3746e7c 100644
--- a/packages/hadron-build/lib/target.js
+++ b/packages/hadron-build/lib/target.js
@@ -1,23 +1,20 @@
 // eslint-disable-next-line strict
 'use strict';
 const chalk = require('chalk');
-const childProcess = require('child_process');
-const download = require('download');
 const fs = require('fs');
 const _ = require('lodash');
 const semver = require('semver');
 const path = require('path');
-const { promisify } = require('util');
 const normalizePkg = require('normalize-package-data');
 const parseGitHubRepoURL = require('parse-github-repo-url');
 const ffmpegAfterExtract = require('electron-packager-plugin-non-proprietary-codecs-ffmpeg').default;
 const windowsInstallerVersion = require('./windows-installer-version');
 const debug = require('debug')('hadron-build:target');
-const execFile = promisify(childProcess.execFile);
 const which = require('which');
 const plist = require('plist');
 const { sign, getSignedFilename } = require('./signtool');
 const tarGz = require('./tar-gz');
+const { notarize } = require('./mac-notary-service');
 
 function _canBuildInstaller(ext) {
   var bin = null;
@@ -562,7 +559,6 @@ class Target {
     };
 
     this.createInstaller = async() => {
-      const appDirectoryName = `${this.productName}.app`;
       const appPath = this.appPath;
 
       {
@@ -580,58 +576,32 @@ class Target {
         await fs.promises.writeFile(plistFilePath, plist.build(plistContents));
       }
 
-      if (process.env.MACOS_NOTARY_KEY &&
-          process.env.MACOS_NOTARY_SECRET &&
-          process.env.MACOS_NOTARY_CLIENT_URL &&
-          process.env.MACOS_NOTARY_API_URL) {
-        debug(`Signing and notarizing "${appPath}"`);
-        // https://wiki.corp.mongodb.com/display/BUILD/How+to+use+MacOS+notary+service
-        debug(`Downloading the notary client from ${process.env.MACOS_NOTARY_CLIENT_URL} to ${path.resolve('macnotary')}`);
-        await download(process.env.MACOS_NOTARY_CLIENT_URL, 'macnotary', {
-          extract: true,
-          strip: 1 // remove leading platform + arch directory
-        });
-        await fs.promises.chmod('macnotary/macnotary', 0o755); // ensure +x is set
+      const isNotarizationPossible = process.env.MACOS_NOTARY_KEY &&
+        process.env.MACOS_NOTARY_SECRET &&
+        process.env.MACOS_NOTARY_CLIENT_URL &&
+        process.env.MACOS_NOTARY_API_URL;
 
-        debug(`running "zip -y -r '${appDirectoryName}.zip' '${appDirectoryName}'"`);
-        await execFile('zip', ['-y', '-r', `${appDirectoryName}.zip`, appDirectoryName], {
-          cwd: path.dirname(appPath)
-        });
-        debug(`sending file to notary service (bundle id = ${this.bundleId})`);
-        const macnotaryResult = await execFile(path.resolve('macnotary/macnotary'), [
-          '-t', 'app',
-          '-m', 'notarizeAndSign',
-          '-u', process.env.MACOS_NOTARY_API_URL,
-          '-b', this.bundleId,
-          '-f', `${appDirectoryName}.zip`,
-          '-o', `${appDirectoryName}.signed.zip`,
-          '--verify',
-          ...(this.macosEntitlements ? ['-e', this.macosEntitlements] : [])
-        ], {
-          cwd: path.dirname(appPath),
-          encoding: 'utf8'
-        });
-        debug('macnotary result:', macnotaryResult.stdout, macnotaryResult.stderr);
-        debug('ls', (await execFile('ls', ['-lh'], { cwd: path.dirname(appPath), encoding: 'utf8' })).stdout);
-        debug('removing existing directory contents');
-        await execFile('rm', ['-r', appDirectoryName], {
-          cwd: path.dirname(appPath)
-        });
-        debug(`unzipping with "unzip -u '${appDirectoryName}.signed.zip'"`);
-        await execFile('unzip', ['-u', `${appDirectoryName}.signed.zip`], {
-          cwd: path.dirname(appPath),
-          encoding: 'utf8'
-        });
-        debug('ls', (await execFile('ls', ['-lh'], { cwd: path.dirname(appPath), encoding: 'utf8' })).stdout);
-        debug(`removing '${appDirectoryName}.signed.zip' and '${appDirectoryName}.zip'`);
-        await fs.promises.unlink(`${appPath}.signed.zip`);
-        await fs.promises.unlink(`${appPath}.zip`);
+      const notarizationOptions = {
+        bundleId: this.bundleId,
+        macosEntitlements: this.macosEntitlements
+      };
+
+      if (isNotarizationPossible) {
+        await notarize(appPath, notarizationOptions);
       } else {
         console.error(chalk.yellow.bold(
-          'WARNING: macos notary service credentials not set -- skipping signing and notarization!'));
+          'WARNING: macos notary service credentials not set -- skipping signing and notarization of .app!'));
       }
+
       const createDMG = require('electron-installer-dmg');
       await createDMG(this.installerOptions);
+
+      if (isNotarizationPossible) {
+        await notarize(this.installerOptions.dmgPath, notarizationOptions);
+      } else {
+        console.error(chalk.yellow.bold(
+          'WARNING: macos notary service credentials not set -- skipping signing and notarization of .dmg!'));
+      }
     };
   }