Location
Central London

Hours
Full Time

Salary
£64,005 to £66,332 depending on location

About the Role
MI5 keeps the country safe from serious threats like terrorism and attempts by states to harm the UK, its people and way of life. We carry out investigations by obtaining, analysing, and assessing intelligence, and work with partners including MI6 and GCHQ to disrupt these threats. Through our protective security arm, we provide advice and guidance to government, businesses and other organisations about how to keep themselves safe. A role in MI5 means you'll do unique and challenging work in a supportive and encouraging environment, making a real difference to UK national security.

As a Senior Cyber Security Engineer, you'll play a central role in protecting the organisation's digital products, embedding security into how systems are designed and built. The role combines engineering and security expertise, applying practical skills to identify weaknesses, validate controls and help teams deliver secure, resilient systems from the outset.

Working within a highly collaborative environment, you’ll contribute to organisation-wide security capability, tackling complex challenges across a diverse and evolving technology landscape. Early engagement in the development lifecycle is vital, shaping design decisions, influencing architecture and ensuring security is integrated into modern engineering practices.

This role combines technical depth with real influence. Threat modelling, vulnerability assessment and security testing form a core part of the work, applying an adversarial mindset to uncover risks. Just as important is working directly with engineers, architects and stakeholders to resolve those risks, improve practices and raise the organisation's overall security maturity.

You’ll take a "purple team" approach, combining elements of red team testing and defensive security – identifying vulnerabilities and working with teams to fix them, building better, more secure systems.

The role also extends to the wider direction of security engineering: supporting less experienced colleagues, influencing technical decisions and helping stakeholders understand risk, trade-offs and priorities. With a high degree of autonomy, you'll take ownership of complex problems and play a key role in how security is delivered across the organisation.

Benefits
From the moment you join, you’ll be supported to develop your expertise in cyber security through hands-on experience and structured learning. Opportunities include on-demand learning platforms, virtual cyber ranges, formal training aligned to your role, and support to achieve industry-recognised certifications such as SANS, GIAC, CISSP or Offensive Security qualifications. You will also have opportunities to attend UK-based and international security conferences.

As you grow in the role, you’ll build both technical depth and influence, supported by your team, mentoring opportunities and exposure to real-world threat intelligence.

Additional benefits include 25 days annual leave rising to 30 days after 5 years' service, 10.5 days public and privilege holidays, employee performance recognition schemes, dedicated development budget, interest-free season ticket loan, excellent pension scheme, cycle to work scheme, on-site facilities such as gym, restaurant and coffee bars (at some locations), and paid parental and adoption leave.

Experience
Practical experience in a security-focused role such as cyber security engineering, penetration testing or a closely related technical discipline is essential. Experience with real-world systems, identifying and solving security issues, and applying core security principles such as Secure by Design is required. You should have applied techniques like threat modelling, vulnerability assessment or security testing.

About you
You communicate clearly with both technical and non-technical stakeholders and work collaboratively to resolve issues. You are curious, pragmatic, motivated to keep learning, and able to apply your expertise to complex, high-impact challenges.

Qualifications
A STEM degree with relevant experience or a technical role with a strong security focus is desirable. Industry-recognised certifications such as SANS, GIAC, CISSP or Offensive Security qualifications are supported and encouraged.