Senior Machine Learning Engineer, Search

About the role

We are looking for a Senior Machine Learning Tech Lead to drive ranking and personalization for Roku’s next-generation entertainment assistant across the platform. This role sits at the intersection of Search, Recommendations, Conversational Discovery, and Monetization, with the goal of delivering highly engaging, personalized, and context-aware entertainment experiences. You will lead the development of large-scale ML systems that optimize for multiple objectives including user engagement, long-term retention, satisfaction, and monetization. The role requires strong technical leadership, product intuition, and the ability to balance user experience with business impact across diverse discovery surfaces.

Responsibilities

• Lead the technical vision and roadmap for ranking, personalization, and recommendation systems powering Roku’s entertainment assistant
• Develop and deploy state-of-the-art ML models using deep learning, transformers, LLMs, bandits, reinforcement learning, and causal inference techniques
• Build multi-objective optimization systems balancing engagement, retention, relevance, and monetization goals
• Drive innovation in conversational discovery, contextual recommendations, and personalized content experiences across the platform
• Design, run, and analyze online A/B experiments tied to key product and business KPIs
• Architect scalable ML systems, feature platforms, and data pipelines supporting rapid experimentation and long-term growth
• Mentor engineers and provide technical leadership across cross-functional initiatives involving engineering, product, UX, and analytics teams

Requirements

• 8+ years of industry experience (or PhD with 5+ years) applying ML at scale in search, recommendation, ads, personalization, or related domains
• Strong expertise in ranking systems, recommendation systems, retrieval, personalization, and multi-objective optimization
• Experience building large-scale ML systems leveraging deep learning, sequence models, LLMs, reinforcement learning, or bandit frameworks
• Strong product intuition and experience optimizing user engagement, retention, and monetization simultaneously
• Proficiency in Python, Java, or Scala
• Experience with distributed systems and ML infrastructure such as Spark, Airflow, streaming systems, feature stores, and cloud platforms
• Strong technical leadership, system design, communication, and problem-solving skills
• MS or PhD in Computer Science, Statistics, or a related field