How to Secure Microsoft 365 Business Premium: A Practical Guide for Small and Medium Businesses

Microsoft 365 Business Premium is one of the most capable security platforms available to small and medium organisations. It combines identity protection, device management, threat monitoring, secure collaboration and compliance tools in a single subscription. The challenge for most businesses is not the licensing. It is knowing how to configure everything correctly.

If you are asking how to secure Microsoft 365 for your business, the answer is to focus on a few core areas and ensure they work together. When identity, devices, threat detection and data protection are aligned, Microsoft 365 becomes a strong security foundation rather than just an email and document platform.

This guide explains the essential steps every organisation should take when securing Microsoft 365 Business Premium and highlights the controls that make the biggest difference.

1. Secure identity first

Your users’ identities are at the centre of everything. Before looking at devices or apps, make sure account access is protected properly.

The essentials include:

• Enforcing multi-factor authentication for every user
• Blocking legacy authentication protocols
• Challenging or blocking risky sign-ins
• Using separate administrator accounts
• Reviewing who has access to sensitive apps

Conditional Access ties all of these together. It lets you apply rules that determine who can sign in, from where and in what conditions. For example, you can block access from certain countries, require compliant devices or add extra checks for administrators.

When used properly, Conditional Access removes a huge amount of risk with very little disruption for staff.

2. Bring every device under management with Intune

Once identity is secured, the next step is to make sure every device that connects to your data meets a consistent security baseline. Intune is the tool that does this.

With Intune, you can enforce encryption, require up-to-date operating systems, limit local admin access, control application installations and ensure devices meet your compliance rules before they can reach company data.

Intune also improves the way devices are deployed. Windows Autopilot allows new machines to be configured automatically as soon as they are switched on. This removes inconsistent builds and reduces the time spent preparing hardware for new starters.

3. Keep systems healthy with Autopatch

Regular updates are essential for preventing vulnerabilities, but keeping devices consistent can be difficult as teams grow. Autopatch simplifies this by handling updates for Windows, Microsoft 365 apps, Edge and Teams.

It uses staged deployment rings to test changes with a small group first. This reduces disruption and helps you stay protected without creating extra work for your team.

4. Strengthen device protection with Defender for Business

Defender for Business is far more than a standard antivirus tool. It provides threat detection, behavioural analysis, ransomware protection, vulnerability management and automated investigation.

It works best when it is configured through Intune. Policies can be created that define how devices should behave, which threats should be blocked automatically and how alerts are managed. When everything is joined up, Defender for Business offers a level of protection that was once limited to large enterprises.

5. Protect your data inside and outside the organisation

Documents, emails and shared files need to be secured wherever they go. Microsoft 365 includes a set of tools that help with this.

Sensitivity labels can classify and encrypt files so only the right people can open them. Data loss prevention rules can stop sensitive information from being emailed externally or uploaded to the wrong place. SharePoint and Teams controls ensure external sharing is limited and monitored.

These features protect your business without getting in the way of your staff.

6. Apply strong conditions for administrators

Administrative accounts have far greater privileges than normal users and require strict controls. They should use multi-factor authentication, limited sign-in policies and dedicated roles. Logging and auditing should be enabled to track changes and identify unusual behaviour.

A compromised admin account often leads to full tenant compromise, so this area should never be overlooked.

7. Align Microsoft 365 with compliance requirements

Many industries expect a certain level of security. Cyber Essentials, ISO 27001 and sector-specific requirements all rely on good identity, device and data controls. Microsoft 365 Business Premium supports these frameworks through built-in tools such as:

• Secure device configuration
• Identity protection
• MFA and Conditional Access
• Threat detection
• Data classification
• Access control

With the right setup, your Microsoft 365 environment becomes a strong base for passing audits, securing contracts and meeting client expectations.

Putting everything together

Securing Microsoft 365 is not about turning on isolated features. It is about building a consistent and predictable environment where identity, devices, data and threat protection all follow the same rules.

When multi-factor authentication, Conditional Access, Intune compliance, Autopatch and Defender for Business work together, the result is a platform that protects itself. Once data protection, administrative controls and compliance are added, you have a secure foundation that can support growth and meet modern security expectations.

Many organisations have the right licensing but lack the configuration to benefit from it. A secure Microsoft 365 environment is perfectly achievable, but it requires the right structure and a clear understanding of how the pieces fit.

Check your Microsoft 365 environment

To help organisations understand their current security position, we provide a Microsoft 365 self-assessment tool. It highlights gaps, checks core controls such as Conditional Access, Autopatch, Intune and Defender for Business, and provides a clear summary of where improvements can be made.

If your business would like help reviewing or securing your Microsoft 365 tenant, our team is here to support you