diff --git a/.github/workflows/ui_test_job.yml b/.github/workflows/ui_test_job.yml
index 0810fe259a..e1de8e8891 100644
--- a/.github/workflows/ui_test_job.yml
+++ b/.github/workflows/ui_test_job.yml
@@ -48,6 +48,15 @@ on:
       github_access_token:
         description: 'Github Token'
         required: true
+      test_onelogin_basic_auth:
+        description: 'Test OneLogin basic auth'
+        required: false
+      test_onelogin_totp_key:
+        description: 'Test OneLogin totp key'
+        required: false
+      test_onelogin_password:
+        description: 'Test OneLogin password'
+        required: false
 
 defaults:
   run:
@@ -120,6 +129,9 @@ jobs:
         env:
           CYPRESS_baseUrl: ${{ inputs.base_url }}
           CYPRESS_RECORD_KEY: ${{ secrets.cypress_record_key }}
+          CYPRESS_TEST_ONELOGIN_BASIC_AUTH: ${{ secrets.test_onelogin_basic_auth }}
+          CYPRESS_TEST_ONELOGIN_TOTP_KEY: ${{ secrets.test_onelogin_totp_key }}
+          CYPRESS_TEST_ONELOGIN_PASSWORD: ${{ secrets.test_onelogin_password }}
           GITHUB_TOKEN: ${{ secrets.github_access_token }}
         run:
           yarn run cypress:parallel-with-specs --spec ${{ inputs.specs }}
diff --git a/.github/workflows/workflow_pr.yml b/.github/workflows/workflow_pr.yml
index dced46a5c4..0ed8c42073 100644
--- a/.github/workflows/workflow_pr.yml
+++ b/.github/workflows/workflow_pr.yml
@@ -145,6 +145,9 @@ jobs:
       aws_secret_access_key: ${{ secrets.AWS_SECRET_ACCESS_KEY_ACTIONS }}
       cypress_record_key: ${{ secrets.CYPRESS_RECORD_KEY }}
       github_access_token: ${{ secrets.GITHUB_TOKEN }}
+      test_onelogin_basic_auth: ${{ secrets.TEST_ONELOGIN_BASIC_AUTH }}
+      test_onelogin_totp_key: ${{ secrets.TEST_ONELOGIN_TOTP_KEY }}
+      test_onelogin_password: ${{ secrets.TEST_ONELOGIN_PASSWORD }}
 
   always_remove_ingress:
     name: Remove CI ingress from environment
diff --git a/cypress/smoke/smoke.cy.js b/cypress/smoke/smoke.cy.js
index fa97ac39c6..ca63b6ce72 100644
--- a/cypress/smoke/smoke.cy.js
+++ b/cypress/smoke/smoke.cy.js
@@ -1,20 +1,51 @@
+const { TOTP } = require("totp-generator");
+
 describe('Smoke tests', () => {
-    describe('external dependencies', () => {
-        describe('UID service', () => {
-            it('request signing and base URL are configured correctly', () => {
-                cy.request('/health-check/dependency').should((response) => {
-                    expect(response.status).not.to.eq(403)
-                })
-            })
+  describe('external dependencies', () => {
+    describe('UID service', () => {
+      it('request signing and base URL are configured correctly', () => {
+        cy.request('/health-check/dependency').should((response) => {
+          expect(response.status).not.to.eq(403)
         })
+      })
     })
+  })
 
-    describe('app', () => {
-        it('is available', () => {
-            cy.visit('/')
+  describe('app', () => {
+    it('is available', () => {
+      cy.visit('/')
 
-            cy.get('h1').should('contain', 'Make and register a lasting power of attorney (LPA)');
-            cy.contains('a', 'Start');
-        })
+      cy.get('h1').should('contain', 'Make and register a lasting power of attorney (LPA)');
+
+      if (Cypress.config().baseUrl.includes('1221mlpab18')) {
+        cy.intercept('https://signin.integration.account.gov.uk/**', (req) => {
+          req.headers['Authorization'] = 'Basic ' + btoa(Cypress.env('TEST_ONELOGIN_BASIC_AUTH'));
+        });
+
+        cy.contains('a', 'Start').click({ timeout: 40000 });
+
+        const { otp } = TOTP.generate(Cypress.env('TEST_ONELOGIN_TOTP_KEY'));
+
+        cy.origin('https://signin.integration.account.gov.uk', { args: { token: otp } }, ({ token }) => {
+          cy.url().should('contain', '/sign-in-or-create', { timeout: 30000 });
+
+          cy.contains('Sign in').click();
+          cy.get('[type=email]').type('opgteam+modernising-lpa@digital.justice.gov.uk');
+          cy.get('form').submit();
+          cy.get('[type=password]').type(Cypress.env('TEST_ONELOGIN_PASSWORD'));
+          cy.get('form').submit();
+
+          cy.get('[name=code]').type(token);
+          cy.contains('button', 'Continue').click();
+        });
+
+        cy.origin('https://preproduction.app.modernising.opg.service.justice.gov.uk', () => {
+          cy.url().should('contain', '/dashboard');
+          cy.contains('Manage your LPAs');
+        });
+      } else {
+        cy.contains('a', 'Start');
+      }
     })
+  })
 })
diff --git a/package.json b/package.json
index 5266118757..3b96d6b912 100644
--- a/package.json
+++ b/package.json
@@ -20,7 +20,8 @@
         "esbuild": "^0.20.0",
         "govuk-frontend": "5.3.1",
         "jquery": "^3.6.1",
-        "sass": "^1.56.1"
+        "sass": "^1.56.1",
+        "totp-generator": "^1.0.0"
     },
     "devDependencies": {
         "axe-core": "^4.6",
diff --git a/yarn.lock b/yarn.lock
index ec094c79e8..7d98bd1e7c 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1501,6 +1501,11 @@ jsprim@^2.0.2:
     json-schema "0.4.0"
     verror "1.10.0"
 
+jssha@^3.3.1:
+  version "3.3.1"
+  resolved "https://registry.yarnpkg.com/jssha/-/jssha-3.3.1.tgz#c5b7fc7fb9aa745461923b87df0e247dd59c7ea8"
+  integrity sha512-VCMZj12FCFMQYcFLPRm/0lOBbLi8uM2BhXPTqw3U4YAfs4AZfiApOoBLoN8cQE60Z50m1MYMTQVCfgF/KaCVhQ==
+
 lazy-ass@^1.6.0:
   version "1.6.0"
   resolved "https://registry.yarnpkg.com/lazy-ass/-/lazy-ass-1.6.0.tgz#7999655e8646c17f089fdd187d150d3324d54513"
@@ -2117,6 +2122,13 @@ to-regex-range@^5.0.1:
   dependencies:
     is-number "^7.0.0"
 
+totp-generator@^1.0.0:
+  version "1.0.0"
+  resolved "https://registry.yarnpkg.com/totp-generator/-/totp-generator-1.0.0.tgz#00a3532dbece7a08950a6318c1317bff3b609510"
+  integrity sha512-Iu/1Lk60/MH8FE+5cDWPiGbwKK1hxzSq+KT9oSqhZ1BEczGIKGcN50bP0WMLiIZKRg7t29iWLxw6f81TICQdoA==
+  dependencies:
+    jssha "^3.3.1"
+
 tough-cookie@^4.1.3:
   version "4.1.3"
   resolved "https://registry.yarnpkg.com/tough-cookie/-/tough-cookie-4.1.3.tgz#97b9adb0728b42280aa3d814b6b999b2ff0318bf"