Introduction

Implementing an Information Security Management System (ISMS) is a strategic move for any organization seeking to safeguard its information assets and comply with global standards such as ISO 27001:2025.
This blog provides a complete guide to ISMS design, implementation, and the key framework components required to align with the newest ISO revision.

What Is an ISMS?

An ISMS is a structured framework of policies, controls, processes, and technologies that work together to protect an organization’s information.
It ensures that information remains:

  • Confidential (accessible only to authorized individuals)
  • Integral (complete and accurate)
  • Available (accessible when needed)

A well-designed ISMS supports operational resilience, customer trust, and legal/regulatory compliance.

Key Stages of ISMS Implementation

Below is a practical step-by-step approach organizations can follow when implementing an ISMS aligned with ISO 27001:2025.

  1. Scoping and Context of the Organization

Define the boundaries of your ISMS, including:

  • Business processes covered
  • Physical locations
  • Information assets
  • Third-party dependencies
  • Regulatory requirements
  • Stakeholders and expectations

This provides clarity on what the ISMS should protect.

  1. Leadership Commitment & Governance Structure

ISO 27001:2025 emphasizes leadership involvement.
Key leadership roles include:

  • Appointing an ISMS manager
  • Providing resources
  • Approving policies
  • Ensuring a culture of security
  • Reviewing ISMS performance

Good governance is the foundation of a successful ISMS.

  1. Information Asset Inventory & Risk Assessment

Identify and classify all information assets: data, applications, hardware, cloud services, and documentation.

Then perform a risk assessment to evaluate:

  • Threats
  • Vulnerabilities
  • Impact levels
  • Likelihood
  • Existing controls

This allows you to create a clear Security Risk Treatment Plan (SRTP).

  1. Selecting & Designing Controls (ISO 27001:2025 Annex)

Based on your risk treatment plan, select appropriate controls from the updated annex controls.

Controls may include:

  • Access management
  • Backup and recovery
  • Network security
  • Mobile device management
  • Cloud service governance
  • Logging and monitoring
  • Incident response
  • Supplier management

The design of these controls must align with the organization’s structure and technologies.

  1. Developing ISMS Documentation

Documentation is a core aspect of ISO 27001 compliance.
Required documents include:

  • ISMS Policy
  • Information security objectives
  • Standard Operating Procedures (SOPs)
  • Risk assessment & treatment documents
  • Asset register
  • Incident management procedures
  • Audit and management review reports
  • Statement of Applicability (SoA)

Well-structured documentation ensures traceability, clarity, and audit readiness.

  1. Implementation & Training

Implement the designed controls and processes across the organization.

This includes:

  • Employee awareness training
  • Technical configuration
  • Operational roll-out of controls
  • Monitoring tools setup
  • Supplier/partner communication

Training and communication ensure effective adoption.

  1. Performance Evaluation

Organizations must monitor, measure, and evaluate ISMS performance.
This includes:

  • Internal audits
  • Monitoring tools and logs
  • KPI tracking
  • Compliance checks
  • Management reviews

Continuous performance evaluation ensures ongoing improvement.

  1. Continual Improvement

ISO 27001:2025 requires ongoing improvement of the ISMS based on:

  • Audit findings
  • Incident analysis
  • Changing business needs
  • New technologies
  • Updated threats
  • Feedback from stakeholders

A continually improving ISMS remains relevant and effective.

ISMS Framework Overview

An ISMS framework includes the following components:

  1. Policies and Procedures

Provide direction and rules for secure information handling.

  1. Technical Controls

Firewalls, encryption, monitoring tools, access restrictions, SIEM, MFA, and more.

  1. Organizational Controls

Training, audits, incident response teams, governance structures.

  1. Physical Controls

Secure access to buildings, CCTV, badges, visitor logs.

  1. Legal & Regulatory Compliance

GDPR, local data protection acts, contractual obligations, sector standards.

  1. Continuous Monitoring & Risk Management

Ensure the ISMS adapts to evolving risks and new threats.

Conclusion

Implementing an ISMS based on ISO 27001:2025 helps organizations build a secure, resilient, and compliant information security environment. With a clear structure covering design, implementation, documentation, and continuous improvement businesses can protect their information assets, reduce risks, and meet global security expectations.

If your organization needs support designing or implementing an ISMS, Bellieroaster provides end-to-end consultancy, training, and technical implementation services tailored to your needs.