Principal ML Engineer

Principal Machine Learning Engineer

Europe Remote | Up to 135,000 Base + Bonus (c.150,000 OTE)

This is an opportunity to join a growing, profitable AI-driven technology business where machine learning is central to the product and commercial strategy. The role offers a rare blend of technical leadership and hands-on engineering, allowing you to shape the future direction of ML systems while solving complex challenges at scale.

The Company

They are an established technology scale-up that develops advanced machine learning solutions to power highly personalised digital experiences for millions of users worldwide. Operating internationally, the business has grown significantly in recent years and continues to invest heavily in its data and AI capabilities.

Their machine learning teams work on large-scale real-time systems where model performance directly impacts commercial outcomes. With a collaborative engineering culture and strong leadership support, they offer an environment where innovation and experimentation are encouraged.

The Role

As a Principal Machine Learning Engineer, you will provide technical leadership across the machine learning function while remaining closely involved in model development and production systems.

Key responsibilities include:

• Defining technical direction for machine learning systems and frameworks.
• Designing, developing and optimising machine learning models in a large-scale production environment.
• Leading the development of recommendation engines, bidding algorithms and audience targeting systems.
• Building mobile attribution models and solutions focused on customer lifetime value and churn prediction.
• Driving best practice across MLOps, model monitoring, observability and automated retraining.
• Enhancing machine learning infrastructure, experimentation platforms and deployment processes.
• Partnering with engineering leaders and business stakeholders to align machine learning initiatives with commercial objectives.
• Mentoring engineers and contributing to architectural decisions across the wider technology organisation.

Your Skills & Experience

• Strong commercial experience building and owning machine learning systems in production.
• Experience developing and deploying machine learning models at scale.
• Advanced Python skills alongside experience with modern machine learning frameworks such as PyTorch or TensorFlow.
• Excellent understanding of MLOps, model lifecycle management and production machine learning environments.
• Experience working with recommendation systems, predictive modelling, LTV modelling, churn prediction or related machine learning applications.
• Strong software engineering fundamentals with a focus on scalability, performance and reliability.
• Ability to communicate technical concepts effectively to both technical and non-technical stakeholders.
• Experience within AdTech, programmatic advertising, real-time bidding or demand-side platforms would be highly beneficial.

Nice to Have

• PhD in a STEM discipline.
• Experience within DSP environments.
• Exposure to mobile advertising, attribution modelling or related performance marketing technologies.

What They Offer

• 4.5-day working week with Friday afternoons off.
• Flexible remote working policy.
• Longevity bonus awarded every two years.
• Strong work-life balance and employee wellbeing initiatives.
• The opportunity to shape machine learning strategy within a growing and profitable technology business.
• Clear opportunities for progression and increased technical influence.

Interview Process

1. Introductory conversation with the Talent Acquisition team.
2. Take-home technical assessment.
3. Technical interview and assessment review with senior machine learning engineers.
4. Interview with the CTO.
5. Final executive leadership interview.

How to Apply

If you are an experienced Principal Machine Learning Engineer looking to combine technical leadership with hands-on machine learning development, please apply to learn more about this opportunity.