Principal Machine Learning Scientist ID49000 in London

Are you passionate about building recommendation systems that go beyond the obvious? Enjoy tackling complex ML challenges where research meets real-world impact? Want Principal-level influence without the people management? Our client, a major global digital platform, is looking for a Principal Machine Learning Scientist to help advance its search, ranking and recommendation capabilities.

You’ll work on complex machine learning challenges involving millions of users, billions of data points and sophisticated personalisation models. It’s an opportunity to combine advanced ML research with production engineering, helping develop intelligent systems that make discovery faster, smarter and more relevant.

Why This Role is Great

• Lead ML innovation across search, retrieval, ranking and recommendations, shaping technical approaches from concept to deployment.
• Explore advanced modelling techniques, including Multi-Task Learning (MTL), MMoE, sequential recommendations and representation learning.
• Engineer for scale, developing low-latency retrieval pipelines, vector search and high-performance ML architectures.
• Work with emerging AI technologies, including Graph Neural Networks, knowledge graphs, Generative AI and agentic systems.
• Solve meaningful optimisation challenges, balancing competing objectives through experimentation and intelligent model design.
• Influence technical decisions, collaborating with experienced engineers, scientists and product specialists while mentoring others.

You’ll remain a hands-on individual contributor, with the autonomy to explore new approaches and help establish best practices.

About You

You could currently be a Staff ML Engineer, Principal ML Scientist, Applied Scientist, Research Scientist or Senior ML Technical Lead. We’re particularly interested in experience involving:

• Search, ranking, recommendation or personalisation systems.
• Deep learning, MTL, MMoE or multi-objective optimisation.
• Python, PyTorch or TensorFlow.
• Distributed computing and cloud technologies such as Spark, Ray, AWS or GCP.
• Designing and deploying machine learning systems in production.

Experience with GNNs, LLMs, Agentic AI or large-scale consumer platforms would be an added advantage. Around 8+ years of relevant industry experience is a useful benchmark, although the quality and complexity of your work matter more than the number. A relevant postgraduate qualification is welcomed, but equivalent practical expertise is equally worth discussing.

Don’t match everything? If you’ve built sophisticated ML systems and enjoy challenging technical problems, we’d still like to hear from you.

The Package

Base salary: Up to £190,000. Annual bonus: 17.5%. First-year package: Up to approximately £250,000. Location: London, hybrid working with approximately one office day per week.

Additional benefits include flexible working, professional development opportunities and wellbeing support. The first-year package includes a one-off sign-on bonus and assumes the applicable annual bonus is paid.

Interested? If you’re looking for a senior ML role where you can tackle ambitious technical challenges, experiment with advanced AI techniques and make a meaningful impact, this is worth exploring. Humand Talent and our client are equal opportunities employers committed to inclusive recruitment. We welcome applications from people of all backgrounds, including those with transferable skills who may not meet every requirement.