Location
London

Hours
Full Time

Salary
Negotiable

About the Role
As a Principal Machine Learning Scientist at Tripadvisor, you will be the technical anchor for our core discovery engine. You will lead the machine learning strategy and execution that powers how millions of users search for, discover, and organize their complex travel itineraries. This high-impact role bridges cutting-edge AI research and production-grade engineering, directly influencing multi-objective business outcomes such as user engagement and booking conversion. You will tackle complex, ambiguous problems at the intersection of deep multi-task ranking, sequential user modeling, and graph-based travel recommendations. If you are passionate about building state-of-the-art AI systems and mentoring a high-performing team of scientists, this role is for you.

What You'll Do
- Drive the technical roadmap for Search, Retrieval, Ranking, and Recommendation systems within the Trips vertical.
- Translate high-level business goals into concrete ML architectures and scalable production systems.
- Design, prototype, and scale next-generation recommendation and ranking models.
- Solve complex, non-linear travel journeys using sequential recommenders, representation learning, and deep multi-objective frameworks.
- Oversee deployment of low-latency, high-throughput retrieval and ranking pipelines capable of processing billions of travel data points in real-time.
- Partner closely with Product Managers, Engineering Leads, and Data Science peers to optimize multi-task business objectives.
- Act as the primary technical authority for ML initiatives within the Trips vertical.
- Mentor and coach senior and mid-level ML scientists, fostering a culture of technical excellence and best practices in MLOps, A/B testing, data privacy, and code quality.

About Tripadvisor
The Tripadvisor Group connects people to experiences worth sharing and aims to be the world’s most trusted source for travel and experiences. Leveraging our brands, technology, and capabilities, we connect our global audience with partners through rich content, travel guidance, and two-sided marketplaces for experiences, accommodations, restaurants, and other travel categories. Our subsidiaries include a portfolio of travel brands such as Tripadvisor, Viator, and TheFork.

What We Offer
Competitive compensation packages including base salary and annual bonuses.
Flexible work arrangements with a remote-friendly approach and optional on-site presence.
Flexible schedule promoting work-life balance.
Donation matching for qualifying charitable contributions.
Tuition assistance for career development.
Lifestyle benefit to spend on travel, wellness, or other personal priorities.
Travel perks including discounts.
Employee assistance program providing resources for life’s challenges.
Health benefits with competitive coverage.
Generous referral scheme rewarding successful candidate referrals.

Our Cultural Pillars
Traveler first: We create value for travelers and enable our partners to unlock this value.
Execution is our edge: We act fast, experiment, learn, and iterate with agile, data-driven, scalable solutions.
We succeed together: We collaborate with empathy and humility, challenge assumptions, give feedback, and celebrate collective achievements.
We strive to create an accessible and inclusive experience for all candidates.

Experience
8+ years of industry experience developing and deploying large-scale ML models in production environments, with a proven track record of shipping systems at the scale of millions of active users.
Strong background in multi-task learning, sequential recommendation systems, representation learning, and scalable ML architectures.
Experience with distributed computing frameworks (Spark, Ray) and cloud infrastructure (AWS/GCP).
Preferred experience with Graph Neural Networks, knowledge graphs, agentic AI, generative AI, and working in E-commerce, Travel Tech, or Two-Sided Marketplaces.
Demonstrated academic or industry contributions, including publications in top-tier AI/IR conferences or open-source ML projects.

About you
Passionate about building state-of-the-art AI systems and mentoring teams.
Strong leadership skills with the ability to translate business goals into technical solutions.
Collaborative mindset to work effectively with cross-functional teams.
Committed to technical excellence, best practices, and fostering an inclusive culture.

Qualifications
Ph.D. or Master’s degree in Computer Science, Machine Learning, Statistics, or a highly quantitative field.
Mastery of Python and deep learning frameworks such as TensorFlow and PyTorch.