Key takeaways
- Microsoft Sentinel is cloud-only and billed per GB of data ingested. Splunk Enterprise Security runs in Splunk Cloud or on your own servers.
- Sentinel connects natively to Microsoft 365, Azure and Defender, and several Microsoft sources are free to ingest.
- Splunk offers workload-based and ingest-based pricing, among other models, and quotes through its sales team.
- Sentinel queries use KQL (Kusto Query Language), while Splunk uses SPL (Search Processing Language), so the skills don’t transfer directly.
- Microsoft’s SIEM migration experience maps Splunk detections to Sentinel rules, but detections it can’t match still need rebuilding by hand.
Microsoft Sentinel and Splunk Enterprise Security are two of the most widely used SIEMs, but they suit different environments, budgets and teams. This guide compares them side by side on deployment, pricing, data sources, automation and the skills each one needs, so you can see which fits your business. It ends with a step-by-step guide to moving from Splunk to Sentinel, and for a full introduction to Sentinel itself, see our Microsoft Sentinel SIEM guide.
What is the difference between Microsoft Sentinel and Splunk?
Microsoft Sentinel is Microsoft’s cloud-native SIEM. It’s billed per GB of data ingested and built into Azure and the Microsoft Defender portal. Splunk Enterprise Security is Splunk’s SIEM, available as Splunk Cloud or installed on your own infrastructure, and Splunk has been part of Cisco since Cisco completed its acquisition on 18 March 2024. Both detect and investigate threats across many data sources. The main differences are where they run, how they’re priced and which ecosystem they fit best.
Microsoft Sentinel vs Splunk Enterprise Security at a glance
What the table means in practice
If most of your systems already run on Microsoft 365 and Azure, Sentinel starts with an advantage: native connections, free data sources and one portal shared with Defender. If you need your SIEM on your own servers, or you’ve invested years in Splunk searches and dashboards, Splunk keeps that flexibility. For a wider look at running a SIEM in the cloud or on your own hardware, read cloud SIEM vs on-premises SIEM
How does Microsoft Sentinel pricing compare with Splunk?
Microsoft Sentinel publishes per-GB list prices: $4.30 per GB on pay-as-you-go in East US, or less on commitment tiers. Splunk prices Enterprise Security mainly by workload, meaning the computing power used to search and analyse data, or by the amount of data ingested per day. It quotes through its sales team rather than publishing a list price. That makes a fair comparison a matter of getting a quote for your own data volume, not comparing two price lists.
How each pricing model works
Sources: Microsoft Learn: Sentinel billing and Splunk pricing models, checked on 31 October 2026.
What each model rewards
- Sentinel rewards filtering. Because you pay for every GB you ingest, the savings come from dropping low-value data before it arrives and sending rarely searched logs to the cheaper data lake.
- Splunk workload pricing rewards light searching. Because you pay for compute rather than volume, you can bring in more data, but heavy searching and many scheduled searches raise the cost.
- Splunk ingest pricing works like Sentinel’s. Cost follows daily volume, with a lower rate per GB at higher volumes.
The costs both share
Neither price covers the people who run the SIEM. Analysts to watch incidents around the clock, and engineers to tune detections, usually cost more than the platform itself, whichever SIEM you choose. For a full breakdown of Sentinel’s prices, tiers and worked monthly bills, read our guide to Microsoft Sentinel pricing.
Which is better for Microsoft 365 and Azure environments?
Microsoft Sentinel is usually the better fit for businesses that run mainly on Microsoft 365 and Azure. Those sources connect natively, several are free to ingest, and Microsoft Defender alerts land in the same incident queue as everything else. Splunk can monitor the same Microsoft services, but it does so through add-ons and APIs, and with no free Microsoft data.
Where Sentinel has the advantage in a Microsoft estate
- Native connectors. Microsoft 365, Entra ID, Defender and Azure connect to Sentinel through built-in data connectors, often with a few clicks and no extra infrastructure.
- Free Microsoft data. Azure Activity logs, Office 365 audit logs and Defender alerts cost nothing to ingest, and Microsoft 365 E5 customers get up to 5 MB per user per day of extra Microsoft 365 data free.
- One portal with Defender. After 31 March 2027, Sentinel is worked from the Microsoft Defender portal, where Sentinel and Defender XDR incidents share one queue. Analysts see the whole attack without switching tools.
- No platform to run. Sentinel runs inside your own Azure subscription, so there are no servers, storage or upgrades to manage.
- Simple access for managed providers. Sentinel supports Azure Lighthouse, so a managed service provider can work in your workspace while the data stays in your tenant, and you can revoke access at any time.
Where Splunk still fits a Microsoft business
A Microsoft-first business can still run Splunk well. It makes sense if Splunk is already in place, if the team knows SPL, or if Splunk also handles IT and application monitoring. In that case, the cost of switching may outweigh the benefits above. To see how Sentinel and Microsoft’s own Defender products split the work, read Microsoft Sentinel vs Defender XDR.
When is Splunk the better choice?
Splunk is often the better fit in three situations: when data has to stay on your own servers or off the internet, when your team already has years of SPL searches and dashboards, or when Splunk also handles IT and application monitoring. In those cases, Splunk’s flexibility outweighs Sentinel’s advantages in a Microsoft estate.
1. On-premises or isolated environments
Microsoft Sentinel only runs in the cloud. Splunk Enterprise Security can be installed on your own infrastructure, including networks with no internet connection. Some government, defence, energy and critical infrastructure organisations need exactly that.
2. An existing Splunk investment
Years of saved searches, dashboards, reports and custom detections written in SPL take real effort to rebuild in KQL. When a mature Splunk deployment is working well, the cost and risk of migrating can be greater than the savings.
3. Security and IT monitoring on one platform
Many organisations use Splunk for application performance, infrastructure and IT operations as well as security. Keeping security on the same platform means one data pipeline and one set of skills across both teams.
4. An estate that is mostly outside Microsoft
If most of your systems run on AWS, Google Cloud, Linux or third-party SaaS, Sentinel’s free Microsoft sources and native Microsoft connectors count for less. Both SIEMs then compete on the same terms.
Either way, it needs watching
Choosing the right SIEM is only half the decision. Both raise incidents that someone has to investigate at any hour, and both need detections tuned as your environment changes. CyberQuell’s SOC monitoring and response service runs on Microsoft Sentinel, Splunk, or the SIEM you already have. Book a call with CyberQuell to have your SIEM monitored 24/7, whether it runs on Microsoft Sentinel or Splunk, with a 15-minute response SLA on critical and high-severity alerts.
How do you migrate from Splunk to Microsoft Sentinel?
Microsoft’s SIEM migration experience reads your exported Splunk detections and recommends matching Microsoft Sentinel analytics rules, Defender XDR detections and data connectors. Detections it can’t match are rebuilt by hand in KQL, and both SIEMs run side by side until Sentinel is proven. Microsoft made an AI-assisted version of the tool generally available in April 2026 for Splunk and QRadar migrations.
Six steps to move from Splunk to Microsoft Sentinel
- Plan what to move. Decide which data sources, detections, dashboards and automations you actually need. Microsoft’s migration planning guide covers how to scope each one.
- Export your Splunk detections. Export your Splunk alerts and saved searches. Exporting all of them needs a Splunk admin role.
- Run the SIEM migration experience. Upload the export to the SIEM migration experience from the SOC Optimization area of the Defender portal. It recommends best-fit Sentinel detections, Defender XDR detections and the data connectors you’ll need, and produces a downloadable report of anything it couldn’t match.
- Leave the dead weight behind. Don’t migrate every detection. Microsoft advises reviewing rules that haven’t fired in the last six to twelve months and dropping low-value alerts rather than rebuilding them.
- Rebuild what didn’t translate. Rewrite unmatched detections as KQL analytics rules, using Microsoft’s guide to mapping Splunk detection rules. Test each rule against real data before you rely on it.
- Run both, then switch over gradually. Connect your sources to Sentinel and run both SIEMs side by side until Sentinel’s detections are proven. Then retire Splunk sources one at a time while you watch Sentinel’s ingestion cost.
What usually takes the longest
The tool speeds up detection mapping, but three things still take people and time:
- custom detections that need rewriting from SPL to KQL
- dashboards and reports that need rebuilding as Sentinel workbooks
- retraining analysts on a new query language and portal
Watch your ingestion costs from the first connector onwards. Our guide to Microsoft Sentinel pricing explains how to filter data and pick the right tier as volume builds.
What skills does each SIEM need?
Microsoft Sentinel teams need KQL and Azure skills. Splunk teams need SPL and, for self-hosted Splunk, the skills to run the servers and storage underneath. Whichever you choose, both need analysts to tune detections and watch incidents around the clock, and that’s usually the harder part to staff.
Skills by platform
The skill both need most
Writing queries is learnable. The harder part to staff is coverage:
- analysts who triage incidents at night and at weekends
- engineers who tune rules so real threats don’t get lost among false alarms
- someone who notices when a data source quietly stops sending logs
Our Microsoft Sentinel SIEM guide breaks down what it takes to run Sentinel, task by task.
Switching means retraining
KQL and SPL do similar jobs but differ in syntax and approach. A team moving from Splunk to Sentinel should plan time for analysts to learn KQL before Splunk is switched off. Microsoft’s Sentinel skill-up training is a free place to start.
Final thoughts
Microsoft Sentinel and Splunk Enterprise Security are both strong SIEMs, and the better choice comes down to where your data lives and what your team already knows. Sentinel has a clear advantage in a Microsoft 365 and Azure estate: native connectors, free Microsoft data, published per-GB prices and one portal shared with Defender. Splunk keeps its edge where data must stay on your own servers, where years of SPL work already exist, or where Splunk also runs IT monitoring.
If you do move from Splunk to Sentinel, Microsoft’s migration tool takes much of the effort out of mapping detections. Plan for the parts it can’t do: rewriting custom rules, rebuilding dashboards and retraining analysts on KQL. Whichever SIEM you run, it only protects you when someone is watching its incidents and tuning its rules. Our Microsoft Sentinel SIEM guide covers what that takes day to day.
Book a call with CyberQuell to get your SIEM monitored 24/7, with a 15-minute response SLA on critical and high-severity alerts and your workspace kept in your own tenant.
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