Senior Information Security Officer in London

We’re looking for a skilled Senior Information Security Officer to join Definely at a pivotal stage of growth. In this role, you’ll take ownership of implementing and maintaining our security standards, supporting compliance programs, and promoting secure practices across engineering and business teams.

You’ll play a key role in ensuring our systems and processes align with ISO 27001 and SOC 2 requirements, contributing to risk assessments, and supporting incident response activities. Working closely with product and engineering teams, you’ll help embed security into the design of our Microsoft Word add-ins and AI-driven features.

As we scale, you’ll also provide IT support across the business, helping to manage devices, onboard new team members, and support day-to-day IT operations to ensure our people can work securely and efficiently. This is an exciting opportunity to have a direct impact on the security posture of a fast-growing LegalTech company, helping safeguard enterprise customers’ most sensitive data while also shaping how we scale IT and security together.

What you'll do:

• Governance & Compliance
  • Own and evolve Definely’s Information Security Management System (ISMS).
  • Lead ISO 27001 and SOC 2 Type II audits, ensuring controls remain effective.
  • Drive readiness for ISO/IEC 42001 AI certification.
  • Apply prior experience successfully obtaining ISO and SOC certifications.
  • Manage customer due diligence requests and run Definely’s SafeBase-powered Trust Center; streamline customer security questionnaires, DPAs, and RFP security sections.
• Product & Engineering Partnership
  • Embed secure SDLC practices across product teams, from design to release.
  • Perform threat modelling, define non-functional security requirements, and review designs for security impact.
  • Guide security considerations in our AI/LLM-enabled products.
• Risk & Incident Management
  • Own the company-wide incident response plan and lead tabletop exercises.
  • Perform ongoing risk assessments, vendor security reviews, and DPIAs.
  • Ensure strong access management, secrets management, and cloud security hygiene.
• IT Support & Operations
  • Provide day-to-day IT support for employees, including device management, troubleshooting, and access provisioning.
  • Support onboarding and offboarding processes to ensure secure and efficient setup of accounts, devices, and permissions.
  • Help scale internal IT processes and tooling as the company grows.
• Enablement & Communication
  • Deliver security training and awareness across the company.
  • Communicate risks and incidents clearly to technical and non-technical stakeholders.

What you'll bring:

• Proven experience in information security within a SaaS or product led environment.
• Strong track record of delivering ISO 27001, SOC 2, or similar certifications, with interest in ISO/IEC 42001 AI standards.
• Experience with compliance tooling such as Drata and working with ISO auditors, ideally in the UK.
• Solid understanding of GDPR and data protection best practices.
• Deep knowledge of secure SDLC, threat modelling, and securing AI and LLM based systems.
• Strong cloud security expertise across Azure or AWS, including access control, secrets management, and incident response.
• Experience running IT operations in a scaling business, including device management, SaaS tooling, and identity systems such as SSO and IAM.
• Excellent communication skills, with the ability to work cross functionally and manage customer security and due diligence processes.
• Relevant certifications such as CISSP, CISM, CCSK, or ISO 27001 Lead Auditor, and a degree in a related field.

What we can offer you:

• Competitive salary & annual bonus.
• Equity in Definely.
• Quarterly team socials + holiday parties.
• Hybrid working + 1 month “work from anywhere”.
• 25 days holiday + bank holidays.
• Take your birthday off.
• £750 annual learning & development budget.
• Private healthcare (incl. dental & optical).
• Enhanced parental leave + Workplace Nursery salary sacrifice scheme.
• Additional perks: Cycle to Work.
• Top-quality equipment.

Definely builds specialist review tools for lawyers working on complex contracts. As AI accelerates the volume and pace of legal decisions, Definely ensures lawyers can understand the full structure of a contract, see the implications of every change, and negotiate with confidence and control.

Launched in September 2020 by Nnamdi Emelifeonwu and Feargus MacDaeid, who worked together at Freshfields, Definely is trusted by over 150+ in-house legal teams and private practice firms, with thousands of users globally. Its customers include top Magic Circle and AMLaw 200 firms, including A&O Shearman, Slaughter and May, DLA Piper, KPMG, Samsung and IKEA.

We recently raised our Series B and are backed by Microsoft, Google, and Octopus Ventures. This is a rare opportunity to shape a new category at the moment it becomes essential.