Microsoft 365 Login: How to Sign In to MS 365
Sign in to Microsoft 365 at microsoft365.com or office.com using your work email address and password. If your organisation uses MFA, you'll also complete a verification step. This guide covers sign-in on desktop, browser and mobile, plus troubleshooting for the most common Microsoft 365 login problems.
Sophie Moore
Operations Manager
How to Sign In to Microsoft 365
The central Microsoft 365 portal is at microsoft365.com. Go there in any browser and click Sign In. Enter your work email address — the one associated with your Microsoft 365 licence, typically in the format yourname@yourcompany.co.uk. Click Next, then enter your password.
If your organisation has enabled Multi-Factor Authentication (MFA), you'll be prompted to verify your identity — usually through the Microsoft Authenticator app on your phone, or via a text message. Complete the verification to finish signing in.
Once signed in, you'll see the Microsoft 365 home screen with tiles for Outlook (email), Teams, Word, Excel, SharePoint, OneDrive and other apps. Clicking any tile opens that application in the browser, or prompts you to open the desktop app if you have one installed.
Microsoft 365 Sign-In on Desktop Applications
Individual Microsoft 365 applications — Outlook, Word, Excel, Teams — each have their own sign-in process, but they all use the same Microsoft 365 account. When you first open any Microsoft 365 app, you'll be prompted to sign in. Use your work email address, and the app will authenticate via the Microsoft identity service.
On Windows devices joined to Azure Active Directory (a managed company device), you may already be signed in automatically — the device's joined account is used to authenticate Microsoft 365 apps without requiring a separate sign-in.
Accessing Microsoft 365 on Mobile
Each Microsoft 365 app is available as a separate mobile app:
- Microsoft 365 (Office) app — access Word, Excel and PowerPoint documents from one app
- Outlook — email and calendar
- Teams — messaging and meetings
- OneDrive — file storage and access
- SharePoint — team document libraries
Download these from the App Store (iOS) or Google Play (Android) and sign in with your work Microsoft 365 account. The Outlook mobile app is particularly popular as it combines email, calendar and Teams meeting joins in one interface.
What to Do If You Can't Sign In
Forgotten Password
On the Microsoft sign-in page, click Forgot my password below the password field. If your organisation has Self-Service Password Reset (SSPR) enabled, you can verify your identity using a backup method (phone, email or Authenticator app) and create a new password immediately. If SSPR isn't set up, contact your IT administrator to reset your password from the Microsoft 365 Admin Centre.
Account Locked
If you see a message that your account is locked, it may have been locked automatically after multiple failed sign-in attempts. Accounts typically unlock automatically after 30 minutes, or an administrator can unlock them immediately from Azure Active Directory in the Microsoft 365 Admin Centre.
MFA Issues
If your MFA prompt isn't arriving (no Authenticator notification, no text), first check that your phone has a signal or internet connection. If the Authenticator app isn't showing a notification, open it manually — you may find a pending approval. If your MFA methods have changed (new phone, new number), contact your IT administrator to update your authentication methods.
Account Doesn't Exist
If Microsoft says your account doesn't exist, verify that you're entering your work email address correctly. If you're a new employee, your IT team needs to create your account and assign a licence before you can sign in. Check with your manager or IT department.
Conditional Access Blocking Sign-In
If you see a message about your device not meeting requirements, your organisation may have conditional access policies requiring a managed or compliant device. This is common in Business Premium and Enterprise tenants. Your IT department can advise on how to get your device enrolled with Intune to meet the compliance requirement.
Staying Signed In
On your personal or work device, Microsoft 365 keeps you signed in by default. You can choose to stay signed in permanently on trusted devices, or sign out after each session for security on shared computers. If you're using a shared device, always sign out after your session and don't save your password in the browser.
If you're regularly prompted to re-enter credentials or complete MFA more frequently than expected, your IT administrator may have configured session timeouts or conditional access policies with shorter token lifetimes. This is a deliberate security control and not a fault.
Need Microsoft 365 Admin Support?
AMVIA manages Microsoft 365 accounts, licences and sign-in policies for UK businesses. Get the admin support your team needs.
Frequently Asked Questions
The main Microsoft 365 portal is at microsoft365.com. You can also sign in at office.com, which redirects to the same portal. Individual apps can be accessed directly — Outlook at outlook.office.com, Teams at teams.microsoft.com, and SharePoint at your organisation's SharePoint domain.
Repeated sign-in prompts are usually caused by session token expiry, conditional access policies requiring re-authentication, or a browser issue clearing cookies. Check whether your IT team has configured short session lifetimes. Clearing the browser cache and cookies can also resolve repeated prompts in the browser version.
Yes. Your Microsoft 365 account can be used on multiple devices simultaneously. You can be signed in on your PC, phone, and tablet at the same time. Your IT administrator can view active sessions and revoke access if a device is lost or stolen from the Azure Active Directory admin portal.
Go to aka.ms/mfasetup and sign in with your Microsoft 365 account. If you can't sign in because your old MFA method is no longer available, contact your IT administrator — they can temporarily disable your MFA requirement from Azure Active Directory to allow you to set up a new method. <strong>Legacy authentication left enabled</strong> "just for that one app" — despite being the vector for 99%+ of password spray attacks <em>(Thehackernews)</em>
The Microsoft 365 portal and most web apps work on Chrome, Edge, Firefox and Safari. Microsoft Edge and Chrome provide the best experience. Some features — particularly in Teams and certain Office online apps — work better in Edge or Chrome than in Firefox or Safari.
Related Reading
Microsoft Teams Login | Sign In Help for Business Users
Sign-in guide for Microsoft Teams specifically, including MFA troubleshooting.
Microsoft 365 Security | Hardening Your Business Tenant
Security configuration for Microsoft 365 including MFA, conditional access and sign-in policies.
What Is Included in Microsoft 365 Business? | Full Breakdown
Everything included in Microsoft 365 Business plans — apps, email, storage and services.