Senior Machine Learning Software Engineer Jobs in Bellevue, WA

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 – 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.

The Unified Personalization Service team is part of Expedia Product & Technology. UPS is building Expedia Group's centralized, real‑time personalization engine across brands and channels, powering ranking, recommendations, retrieval, and other adaptive experiences that help travelers see more relevant, contextual, and useful experiences throughout their journey.

We are looking for a Senior Machine Learning Scientist to help shape the next generation of deep learning systems for personalization, including recommendation, ranking, retrieval, traveler understanding, sequential modeling, and foundation-model-based personalization. This is a senior hands‑on applied science and engineering role for someone who can translate recent research into production‑quality systems, influence technical direction, raise the modeling bar for the team, and mentor other scientists.

• Design, develop, and apply machine learning solutions to real‑world personalization, product, and business problems, translating ambiguous opportunities into scalable models, experiments, and production‑ready capabilities.
• Drive end‑to‑end scientific work across problem formulation, data exploration, feature engineering, model development, evaluation, and iteration, with strong attention to measurable impact.
• Partner closely with engineers, product, and business stakeholders to integrate machine learning solutions into services and workflows, including system design, API design, and data modeling considerations where applicable.
• Use strong technical judgment to select appropriate methods, validate outcomes, and improve model performance, reliability, and operational quality across multiple problem domains.
• Safely integrate and operate AI/ML‑enabled solutions that improve outcomes, including familiarity with AI‑driven systems, tools, or workflows and applying AI/ML concepts to real world products.
• Contribute deep technical expertise across related domains, helping raise scientific and engineering quality through experimentation, documentation, mentoring, and reusable approaches that support broader team effectiveness.

• Bachelor's degree in Computer Science or a related technical field; or equivalent related professional experience.
• 8+ years of relevant professional experience.
• Demonstrated ownership of machine learning solutions at the service or multi‑service level, including problem definition, model development, evaluation, and operationalization within a product or technical domain.
• Strong foundation in machine learning methods, statistical analysis, experimentation, and data‑driven decision making, with hands‑on coding experience in scientific and production‑oriented environments.
• Experience working with cross‑functional partners to deploy technical solutions, with core expectations in scalable model development, data modeling, and integration into software systems.

• Advanced degree in Machine Learning, Computer Science, Statistics, Mathematics, Engineering, or a related quantitative field.
• Experience delivering machine learning solutions at scale, including architecture considerations, production monitoring, model lifecycle management, and operational excellence in live environments.
• Demonstrated ability to influence technical direction within a domain through rigorous experimentation, strong scientific reasoning, pragmatic solution design, and clear communication with cross‑functional partners.
• Strong experience with recommendation, ranking, retrieval, search, personalization, ads, marketplace, e‑commerce, or similarly complex applied ML systems.
• Experience with neural recommendation systems, sequential or session‑based recommendation, transformer‑based recommenders, semantic retrieval, generative retrieval, or representation learning at scale.
• Experience with foundation models, LLMs, embedding models, semantic IDs, hybrid LLM‑recommender systems, two‑stage retrieval and ranking systems, or retrieval‑augmented personalization workflows.
• Relevant academic publications, patents, open‑source contributions, technical blog posts, industry talks, or other contributions to the ML/recommender‑systems community.

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. 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. 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.

Expedia 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 https://careers.expediggroup.com/life.

Expedia 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 https://expedia.service-now.com/askeg?id=job_accommodation.

Expedia 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.

Employment 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 https://careers.expediagroup.com/jobs/.

Expedia 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.