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 and businesses such as Tripadvisor, Viator, and TheFork.

What We Offer
Competitive compensation packages benchmarked against industry data, including base salary and annual bonuses.
Flexible work arrangements with a remote-friendly approach and optional on-site collaboration.
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 interests.
Travel perks including discounts.
Employee assistance programs for personal support.
Comprehensive health benefits with competitive premiums.
Generous referral scheme rewarding successful candidate referrals.

Our Cultural Pillars
Traveler first: We create value for travelers and enable suppliers and partners to unlock this value.
Execution is our edge: We act fast, experiment, learn, iterate, and improve solutions with agility and data-driven prioritization.
We succeed together: We collaborate with empathy and humility, challenge assumptions, give actionable feedback, and celebrate collective achievements.

Experience
8+ years of industry experience developing and deploying large-scale ML models in production environments with millions of active users.
Proven track record of shipping scalable systems.
Strong background in multi-task learning, sequential recommendation systems, and advanced representation learning.
Experience with low-latency, high-throughput retrieval and ranking pipelines.
Hands-on experience with Python, TensorFlow, PyTorch, distributed computing (Spark, Ray), and cloud infrastructure (AWS/GCP).
Preferred experience with Graph Neural Networks, knowledge graphs, or graph embeddings.
Familiarity with Agentic AI frameworks, LLM-driven reasoning, or autonomous planning agents is a plus.
Experience in E-commerce, Travel Tech, or Two-Sided Marketplaces handling non-linear user journeys and constrained inventory.
Strong 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.
Strong leadership and mentorship skills to guide senior and mid-level scientists.
Collaborative mindset with ability to work cross-functionally.
Committed to technical excellence, best practices, and continuous learning.
Data-driven and results-oriented with a focus on multi-objective business outcomes.

Qualifications
Ph.D. or Master’s degree in Computer Science, Machine Learning, Statistics, or a highly quantitative field.