How to Implement ISO 27001 Controls in Practice

 ISO/IEC 27001 controls add value when they work as repeatable routines. In practice, you turn your risk assessment, risk treatment plan, and Statement of Applicability (SoA) into processes and records inside your Information Security Management System (ISMS). This guide explains what ISO 27001 controls are meant to achieve, how to implement them, and what evidence auditors look for, with UK-based examples. 

ISO 27001 controls are practical safeguards that reduce information security risk within your ISMS scope. A control is not just a policy. It is a repeatable way of working, with an owner, a trigger, and records that show it happened.

Controls matter because ISO/IEC 27001 is risk-based, not a fixed checklist. Annex A is a reference set of control objectives and controls, but your control set should follow from the risks you identify. Auditors expect that link to be clear and to see controls operating in day-to-day work, not only on paper. 

You do not need to implement every Annex A control. Annex A is a reference set you use to meet control objectives and treat risks. What ISO 27001 requires is a method: assess risk, decide how you will treat it, and document control choices in the risk treatment plan and the SoA.

The SoA shows which Annex A controls apply to your ISMS scope and why any are excluded. If you cannot justify an exclusion, or if you say a control applies but cannot evidence it, you create avoidable audit findings later.

Implement ISO 27001 controls by turning each control into a simple operating process. Start with what the control is meant to achieve, then define how it works in your organisation.

Implementation usually spans four areas:

1. Policies and procedures: what is allowed, who approves it, and how activities should run
2. Technical safeguards: configurations for access, logging, encryption, and backups
3. Operational processes: ticketing, reviews, change management, and supplier checks
4. Human and organisational controls: training, awareness, and clear responsibilities

For each in-scope control:

1. Define the outcome (what risk it treats and what it aims to achieve)
2. Assign an owner (who keeps it working)
3. Describe the routine (how often it runs and by whom)
4. Decide the evidence (what records you will keep)

This keeps implementation focused on behaviour, processes, and evidence rather than documents alone.

Access control (joiners, movers, leavers) aims to prevent unauthorised access. In practice, this means a joiner–mover–leaver process with approvals, multi-factor authentication for key systems, and regular access reviews. A London SaaS firm routes access requests through a ticketing tool and runs quarterly reviews of live environments. Evidence includes access tickets, approvals, review outputs, and admin access logs.

Asset management aims to ensure you know what you are protecting and who is responsible. Organisations maintain an asset register for key information assets, owners, classifications, and locations, with simple rules for onboarding and retiring assets. A Leeds consultancy tracks laptops, SaaS platforms, and client repositories in a central register with named owners. Evidence includes register exports and onboarding and offboarding records.

Supplier security aims to manage third-party risk. Typical practice is to maintain a supplier register, apply risk ratings, and perform checks for in-scope suppliers such as hosting providers, managed service providers, or payment processors. A Manchester professional services firm uses a short supplier questionnaire for vendors handling client data and reviews high-risk suppliers every six months. Evidence includes questionnaires, contract clauses, risk ratings, and review notes.

Incident management aims to detect, handle, and learn from security incidents. Organisations define a reporting route, triage steps, and post-incident reviews with tracked actions. A UK fintech uses an incident playbook for outages and suspected data exposure, records incidents in a ticketing system, and tracks follow-up actions in an ISMS log. Evidence includes incident tickets, timelines, and action logs.

Policies on their own are not evidence that controls work. Evidence should come from normal operations and show that controls run over time. Useful evidence types include logs, tickets, access review outputs, supplier assessments, audit reports, and management review minutes.

These records should be easy to find, clearly in scope, and linked to relevant risks and Annex A controls in your risk treatment plan and SoA. Common gaps include controls that run informally but leave no records and policies that do not match how work is done.

ISO 27001 expects controls to be monitored and improved, not set once and forgotten. Build light governance into the ISMS so control performance is checked and adjusted.

Monitoring and measurement can include simple metrics such as overdue access reviews, incident response times, or completion rates for key training. Internal audits then sample evidence and confirm controls operate as defined. Management review is where leadership looks at risks, incidents, audit results, and metrics, then decides on priorities, resourcing, and accepted risk.

1. ISO 27001 controls are risk-driven safeguards inside your ISMS scope, not a fixed checklist.
2. Annex A is a reference set of control objectives and controls; you select controls based on your risk assessment and record decisions in the risk treatment plan and SoA.
3. Each control should have a clear outcome, an owner, a routine, and evidence you can produce on request.
4. Evidence should come from day-to-day work, not just policies, and be consistent over time and in scope.

Monitoring, internal audit, and management review keep controls working and support readiness for ISO/IEC 27001 certification.