Senior Machine Learning Scientist

At Expedia Group, we help travelers explore the world, one journey at a time. As a global travel company powered by passionate people, trusted partnerships, and leading technology, we connect travelers, partners, and advertisers through our consumer brands, B2B network, and travel advertising business.Here, you'll do meaningful work that helps millions of people discover, book, and experience travel with more ease, confidence, and joy. Our five Behaviors-Traveler First, Think Big, Operate with Excellence, Ownership Mindset, and Succeed Together-help foster a supportive environment where people can grow their careers and have the flexibility, benefits, and support to do their best work. Join us and build for travelers everywhere.Senior Machine Learning ScientistThe Senior Machine Learning Scientist is responsible for building and evaluating GenAI- and LLM-powered solutions and AI agents that improve post-booking customer experience, including recommendations, customer service, and trip management. Owns end-to-end ML and GenAI projects—from problem framing and data preparation through model/agent design, orchestration, deployment, and continuous evaluation. Applies deep expertise in applied ML, Generative AI, and rigorous experimentation to design robust evaluation frameworks (A/B tests, offline metrics, qualitative assessments) that ensure agents are safe, effective, and aligned with business goals. Partners closely with product, engineering, and operations while mentoring junior scientists and helping define best practices for AI agent development and evaluation.Are you passionate about using machine learning to improve customer experience at scale? Would you like to work in the fast-paced, competitive, customer-focused, and data-rich world of online travel? Our Machine Learning and Data Science team is growing. We are looking for a Senior Machine Learning Scientist to help tackle some of the most complex customer experience problems in the travel domain. You will develop state-of-the-art machine learning and AI solutions to power and enhance the customer experience across highly complex post‑booking recommendations, customer service, and trip management use cases. You will tackle substantial technical challenges, from inference problems on long-tail traveler data to multi-objective optimization in a highly dynamic, operationally complex customer service environment. Your passion for the craft of machine learning, causal inference, and Generative AI will unlock tangible growth for our business by exploiting rich datasets and building effective solutions for travelers and our partners. This is your opportunity to build core algorithms that help Expedia Group's Post Booking organization bring context and intelligence to every step of the traveler journey and redefine what service excellence in travel can be. We are looking for a hands-on senior scientist who can independently drive impactful projects, mentor others, and collaborate closely with partners to make travel more seamless for millions of customers and partners worldwide. In this role, you will:Design & Implement ML Solutions Own the end-to-end ML lifecycle for medium-to-large projects: from problem framing and ideation through research, prototyping, deployment, and post-launch monitoring. Design robust, scalable ML systems (batch and/or streaming) in partnership with engineering, including data pipelines, feature computation, and model serving. Translate ambiguous business problems into well-defined ML problems with clear success metrics and validation strategies. Applied Machine Learning & Data Science Develop, evaluate, and iterate on supervised, unsupervised, and deep learning models for prediction, recommendation, and optimization. Apply causal inference and experimental design (A/B testing) to accurately measure impact and guide decision-making. Read and apply relevant academic and industry research to improve model architectures, training strategies, and evaluation methods. Contribute to defining best practices for experimentation and modeling within the team; help raise the technical bar for ML development. Generative AI & Advanced Techniques Build and iterate on models and applications leveraging GenAI / LLM technologies (e.g., OpenAI, Hugging Face, Anthropic, Gemini) for customer support, content generation, and workflow automation. Use prompting, retrieval-augmented generation, and tool/function-calling patterns to integrate LLMs into production systems. Explore and prototype advanced ML techniques (e.g., reinforcement learning, sequence modeling, transformers) where they can provide clear business value. Statistics, Experimentation & Model Design Design end-to-end modeling approaches, including data selection, feature engineering, algorithm choice, training procedures, and evaluation. Apply statistical rigor in analyzing experiments and observational data; quantify uncertainty, trade-offs, and model risk. Define and monitor offline and online metrics that faithfully reflect business goals (e.g., customer satisfaction, cost-to-serve, operational efficiency). Collaboration, Communication & Visualization Partner closely with product managers, engineers, analysts, and operations to understand requirements, define roadmaps, and align on priorities. Communicate complex technical concepts in a clear, concise way to technical and non-technical stakeholders. Build intuitive dashboards and visualizations to explain model behavior, experiment results, and business impact. Stakeholder & Project Management Lead cross-functional projects involving multiple partners (e.g., product, engineering, operations), driving them from conception to measurable impact. Manage project scope, timelines, and communication, proactively surfacing risks and trade-offs. Mentor junior scientists and engineers on modeling approaches, experimentation, and analytical problem solving. Experience & Qualifications: Experience & Education PhD in a quantitative field (e.g., Computer Science, Statistics, Mathematics, Physics, Economics, Operations Research) and ~3+ years of industry experience; or Master’s degree in a quantitative field with ~5+ years of relevant industry experience. Proven track record of building and deploying ML models that meaningfully impact business metrics in a production environment. Functional & Technical Skills Applied ML & Statistics Strong knowledge of machine learning theory and practice (e.g., supervised learning, representation learning, ranking/recommendation, deep learning). Solid grounding in statistics, experimental design (A/B testing), and basic causal inference; comfortable designing and analyzing online experiments. Able to design end-to-end ML solutions: frame the problem, choose data sources, select algorithms, define evaluation strategies, and iterate based on results. Engineering & Tooling Strong programming skills in Python and its data/ML ecosystem (e.g., pandas, scikit-learn, PyTorch/TensorFlow, PySpark), plus proficiency in SQL. Experience working with cloud-based data/compute platforms and modern data/ML tooling (e.g., Spark, Airflow, feature stores, model serving frameworks). Follow software engineering best practices (version control, code reviews, testing, documentation) and contribute to shared libraries and tooling. Generative AI & Advanced Methods Hands-on experience using GenAI / LLM APIs (e.g., OpenAI, Hugging Face, Anthropic, Gemini) in prototypes or production is highly desired. Familiarity with concepts like prompt engineering, retrieval-augmented generation, function/tool calling, and evaluation of LLM-based systems. Experience with reinforcement learning, bandits, or other advanced ML techniques is a plus. Problem Solving & Communication First-principles problem solver: able to decompose ambiguous problems, identify key assumptions, and design pragmatic, iterative solutions. Excellent written and verbal communication skills; able to tell a compelling story with data and models and influence decisions. Collaborative and customer-obsessed, with the ability to balance scientific rigor and engineering pragmatism in a product environment. Highly Desired Experience Domain experience in customer service, recommendations, personalization, or e-commerce applications. Experience building ML systems for operational decision-making (e.g., contact routing, triage, capacity/effort prediction, workflow optimization). Experience mentoring other scientists or engineers and contributing to technical culture (e.g., brown bags, tech talks, documentation, best practices). If you’re excited about building impactful ML and AI solutions that improve how millions of travelers are served every day, we’d love to hear from you. The total cash range for this position in Seattle is $173,000.00 to $242,500.00. Employees in this role have the potential to increase their pay up to $277,000.00, which is the top of the range, based on ongoing, demonstrated, and sustained performance in the role. The total cash range for this position in San Jose is $187,000.00 to $261,500.00. Employees in this role have the potential to increase their pay up to $299,000.00, which is the top of the range, based on ongoing, demonstrated, and sustained performance in the role.Starting pay for this role will vary based on multiple factors, including location, available budget, and an individual’s knowledge, skills, and experience. Pay ranges may be modified in the future.Benefits and perksExpedia Group offers benefits and perks designed to support employees and their families, including medical, dental, and vision coverage, paid time off, an Employee Assistance Program, wellness and travel reimbursement, travel discounts, and International Airlines Travel Agent Network (IATAN) membership. Learn more about life at Expedia Group at .Accommodation requestsExpedia Group is committed to providing an inclusive and accessible recruiting experience. If you need an accommodation or adjustment due to a disability during the application or recruiting process, please submit a request at .About Expedia GroupExpedia Group includes three flagship consumer brands - Expedia, Hotels.com, and Vrbo - along with a leading B2B travel business and travel advertising offerings. Across our brands and business, we help travelers explore the world with confidence and ease.Important noticeEmployment opportunities and job offers at Expedia Group will always come from Expedia Group's Talent Acquisition and hiring teams. Never share sensitive personal information unless you are confident of the recipient. Expedia Group does not extend job offers via email or messaging tools to individuals with whom we have not made prior contact. Our email domain is @expediagroup.com. The official place to find and apply for roles is .Equal OpportunityExpedia is committed to creating an inclusive work environment with a diverse workforce. All qualified applicants will receive consideration for employment without regard to race, color, religion, gender, gender identity or expression, sexual orientation, national origin, genetics, disability, age, veteran status, or any other characteristic protected by law. This employer participates in E-Verify. The employer will provide the Social Security Administration (SSA) and, if necessary, the Department of Homeland Security (DHS) with information from each new employee's I-9 to confirm work authorization.SummaryLocation: Washington - Seattle Campus; USA - California - San JoseType: Full time