Cyberattacks today rarely rely on advanced hacking. Most breaches start with stolen or guessed passwords. That’s why knowing how to enable MFA in Microsoft 365 is no longer optional. It’s a basic security requirement.
This guide explains what MFA is, why it matters, and exactly how to enable it using the different methods available in Microsoft 365.
What Is MFA in Microsoft 365?
Multi-Factor Authentication (MFA) adds an extra verification step during sign-in. Instead of relying only on a password, users must confirm their identity using something else.
This could be:
In Microsoft 365, MFA is managed through identity services provided by Microsoft.
How MFA Works
User enters username and password
Microsoft verifies credentials
User is prompted for a second factor
Access is granted only after approval
Even if a password is stolen, MFA stops the attacker.
Why You Should Enable MFA
Password-Based Attacks Are Common
Phishing, credential stuffing, and brute-force attacks target passwords. MFA blocks over 99% of these attacks.
Compliance and Security Requirements
Many standards require MFA:
Real-World Breach Prevention
Most Microsoft-reported account compromises involved accounts without MFA enabled.
MFA Options Available in Microsoft 365
Microsoft 365 offers multiple ways to enable MFA. Choosing the right one depends on your environment.
Security Defaults
Per-User MFA
Enable MFA user by user
Legacy method
Limited control
Conditional Access
Most flexible and secure
Based on user, location, device, or app
Requires specific licenses
Prerequisites Before Enabling MFA
Required Admin Roles
You must be:
Global Admin
Security Admin
Conditional Access Admin
License Requirements
User Readiness
Before enabling MFA:
How to Enable MFA in Microsoft 365 Using Admin Center
Step 1: Sign in to Admin Center
Go to:
https://admin.microsoft.com
Step 2: Open Entra Admin Center
Select Identity
Go to Protection
Click Security defaults
Step 3: Enable Security Defaults
This enforces MFA for all users and admins.
How to Enable MFA Using Security Defaults
What Are Security Defaults?
Security defaults are Microsoft’s recommended baseline security settings.
They:
Who Is Affected
All users
No exceptions
Limited customization
Best for small organizations.
How to Enable MFA Using Conditional Access
When to Use Conditional Access
Choose this if you need:
Exceptions
Location-based rules
Device-based enforcement
Create a Conditional Access Policy
Go to Entra Admin Center
Select Conditional Access
Click New policy
Configure the Policy
How to Enable MFA for Individual Users
Per-User MFA
Go to Users
Select Multi-factor authentication
Choose users
Click Enable
Enabled vs Enforced
What Users Experience After MFA Is Enabled
MFA Registration
Users are prompted to register at:
https://aka.ms/mfasetup
Authentication Methods
Common Issues and Troubleshooting
Users Not Prompted for MFA
Possible causes:
MFA Setup Failed
Legacy App Sign-Ins
Older apps may fail. Disable legacy authentication where possible.
Best Practices for Microsoft 365 MFA
Always Enforce MFA for Admins
Admin accounts are prime targets.
Use Authenticator App
More secure than SMS.
Combine MFA with Conditional Access
Layered security reduces risk significantly.
FAQs About Enabling MFA in Microsoft 365
Is MFA free in Microsoft 365?
Yes, basic MFA is included. Advanced Conditional Access requires additional licenses.
Can MFA be bypassed?
Only if policies are misconfigured or legacy authentication is allowed.
How long does rollout take?
From minutes (Security Defaults) to days for phased Conditional Access rollout.
✅ Final Thoughts
Learning how to enable MFA in Microsoft 365 is one of the most impactful security steps you can take. It’s simple to enable, highly effective, and strongly recommended by Microsoft.