Microsoft Sentinel SIEM Setup Guide 2026: Step-by-Step Configuration for UK IT Teams

Introduction

Microsoft Sentinel has become the go-to Security Information and Event Management (SIEM) solution for UK organisations looking to strengthen their security posture. Whether you're managing a small team or enterprise-level infrastructure, understanding how to set up and configure Sentinel properly can save you significant time and money on security incidents.

In 2026, with cyber threats evolving faster than ever, organisations are allocating an average of 12% of their IT budgets to security tools. Sentinel isn't just a monitoring system, it's your first line of defence against increasingly sophisticated attacks targeting UK businesses.

This guide walks you through everything you need to know to get Sentinel up and running properly.

What is Microsoft Sentinel?

Microsoft Sentinel is Microsoft's cloud-native SIEM platform built on Azure. It collects security data from your entire environment, analyses it in real-time, and alerts you to potential threats before they become problems.

Unlike traditional on-premise SIEM solutions, Sentinel operates in the cloud, meaning you don't need to worry about hardware maintenance or complex server setups. It integrates seamlessly with Microsoft 365, Azure, and hundreds of third-party applications.

For UK IT professionals, this means you can monitor your entire security landscape from one dashboard. No more juggling multiple tools or missing critical alerts buried in different systems.

Step 1: Prerequisites and Licensing

Before you begin, you'll need the right setup in place.

Essential requirements:

Azure subscription (Standard tier recommended for SMEs)

Microsoft 365 E5 or Microsoft Defender for Cloud (standalone)

Appropriate admin permissions across your environment

At least one data source to monitor

Licensing considerations in 2026:

Sentinel pricing has remained competitive compared to alternatives like Splunk or IBM QRadar. You're typically looking at around GBP 2.50 per GB of data ingested, with many organisations spending between GBP 500-3,000 monthly depending on their environment size.

This is significantly cheaper than maintaining an on-premise SIEM solution, which can cost upwards of GBP 30,000 annually in hardware and staffing alone.

Step 2: Create Your Azure Workspace

Your Sentinel instance lives within an Azure Log Analytics workspace. Think of this as your security command centre.

Creating your workspace:

1. Navigate to the Azure portal

2. Search for "Log Analytics workspaces"

3. Click "Create"

4. Select your resource group or create a new one

5. Name your workspace (something like "YourCompany-Sentinel-PROD")

6. Choose your region (UK South or UK West for GDPR compliance)

7. Select your pricing tier (Pay-As-You-Go recommended for flexibility)

Pro tip: Name your workspace clearly. If you're managing multiple environments, include the environment type in the name. "AccmeIT-Sentinel-Production" is immediately clearer than "Workspace1".

Step 3: Enable Microsoft Sentinel

Once your workspace exists, enabling Sentinel takes just a few clicks.

1. In your Log Analytics workspace, search for "Microsoft Sentinel"

2. Click "Add Microsoft Sentinel"

3. Select your workspace

4. Review and accept the pricing

Sentinel is now active. You'll see your dashboard populate within minutes as data begins flowing in.

Step 4: Configure Data Connectors

Data connectors are the pipes that feed information into Sentinel. Without them, you're basically running a SIEM with no data.

Critical connectors for UK organisations:

**Microsoft 365 Defender**: Collects alerts from Defender for Endpoint, Office 365, and other Microsoft security tools

**Azure Activity**: Monitors what's happening in your Azure infrastructure

**Microsoft Entra ID (Azure AD)**: Tracks sign-ins, privilege changes, and user activities

**Windows Security Events**: Captures what's happening on your domain-joined machines

**DNS Analytics**: Identifies suspicious domain queries

Configuring a connector (using Microsoft 365 Defender as an example):

1. Go to Sentinel > Data connectors

2. Search for "Microsoft 365 Defender"

3. Click "Open connector page"

4. Click "Connect"

5. Sentinel automatically begins pulling data

Some connectors require agent deployment on machines. For Windows events, you'll deploy the Azure Monitor Agent to your servers. Don't skip this part. You need visibility across your entire estate, not just cloud resources.

Step 5: Create Analytics Rules

Analytics rules are where the magic happens. These rules detect suspicious behaviour and generate alerts.

Key rule types:

**Scheduled**: Runs at set intervals (ideal for looking at trends)

**Near real-time (NRT)**: Triggers within seconds of suspicious activity

**Machine learning**: Uses AI to detect anomalies

Create your first rule:

1. Navigate to Analytics > Create > Scheduled query rule

2. Name it clearly (e.g., "Multiple Failed Login Attempts")

3. Enter your KQL (Kusto Query Language) query

4. Set your query schedule (every 5 minutes is standard)

5. Define alert thresholds

6. Assign severity levels (Informational, Low, Medium, High, Critical)

Sample query to detect multiple failed logins:

```

SigninLogs

| where ResultType != 0

| summarize FailedAttempts = count() by UserPrincipalName, IPAddress

| where FailedAttempts > 10

```

Start with standard rules covering the basics: failed logins, permission changes, suspicious file activities. You can expand once you're comfortable.

Step 6: Set Up Automation and Playbooks

Manual responses don't scale. Playbooks automate your response to incidents.

Practical playbook examples:

Automatically disable compromised user accounts

Create incidents in your ticketing system

Send Slack notifications to your security team

Isolate infected machines from the network

Most organisations benefit from starting with simple playbooks. A Slack notification when a critical alert fires is better than missing the alert entirely because your team didn't see an email.

Step 7: Configure Incident Management

Sentinel creates incidents from your alerts. Proper incident management keeps everything organised.

Best practices:

Assign incidents to team members based on severity

Use consistent naming conventions

Document your investigation findings

Track resolution time metrics

In 2026, UK organisations are investing heavily in incident response. The average cost of a security breach is now GBP 4.45 million, so having structured incident management isn't optional.

Common Mistakes to Avoid

Ingesting too much data without clear purpose (drives costs up needlessly)

Creating alert rules that trigger constantly (your team stops paying attention)

Not monitoring third-party applications your business depends on

Failing to configure role-based access (security tools are targets themselves)

Ignoring data retention policies (compliance nightmare waiting to happen)

Next Steps

Setting up Sentinel is one thing. Running it effectively is another. Many IT teams struggle with tuning their environment, reducing false positives, and knowing what to monitor.

If you're planning to build a security career or need hands-on training in Microsoft 365 and cloud security tools like Sentinel, check out SmoothOps 365. Our Advanced Microsoft 365 course (GBP 1,750) covers practical security configuration, monitoring strategies, and real-world incident scenarios. You'll also get access to our AI Job Search Engine to help you find roles specifically requiring SIEM expertise.

Alternatively, join our free 30-minute live info session to discuss your security learning goals and find the right course for your career path. Book your spot at smoothops365.com/webinar.

Your Sentinel setup is now ready. Monitor, learn, and continuously improve.