Principal Machine Learning Engineer

Riot Data Scientists combine their wide technical expertise across data processing, automation, machine learning ("ML"), artificial intelligence ("AI"), and experimental design to inform decisions and develop data-powered products.

• Define and lead the modeling architecture for personalization, matchmaking, social graph recommendations, and player/community discovery.
• Architect multi-model systems combining skill, preference, trust, and safety signals for fair and meaningful matchmaking
• Develop models for skill inference, player behavior prediction, trust & safety signals, and multi-objective optimization across fairness, latency, and experience quality.
• Build and optimize real-time inference systems for personalized content, store offers, matchmaking, and player interactions at global scale.
• Drive adoption of advanced modeling approaches including contextual bandits, reinforcement learning, graph ML, and session-aware personalization.
• Partner with Data Engineering and Product to shape data schemas, feature pipelines, telemetry standards, and model observability across the ML lifecycle.
• Define Responsible AI standards and implement fairness audits, bias mitigation, transparency, and safety mechanisms for matchmaking and social systems.
• Lead post-launch evaluations of algorithmic impact on player sentiment, community health, and ecosystem stability.
• Set organization-wide standards for model optimization (latency, throughput, memory), multi-model orchestration, and drift detection.
• Mentor senior ML engineers and data scientists, influencing system design, experimentation strategy, and modeling craft across organizations.
• Represent the ML discipline in cross-functional design reviews, driving alignment on technical decisions, data contracts, and long-term strategy

• 10+ years in ML/Applied AI; 3+ years in principal/staff-level technical leadership.
• Experience with large-scale, real-time ML systems (recommendations, personalization, matchmaking).
• Expertise in graph ML, RL, and representation learning.
• Proficiency in PyTorch, TensorFlow, JAX, and modern data/serving tools (Ray, Kafka, Flink, Redis).
• Strong grounding in A/B testing, experiment design, and experience metrics.
• Track record of setting ML strategy and standards across teams.

• Riot focuses on work/life balance, shown by our open paid time off policy and other perks such as flexible work schedules. We offer medical, dental, and life insurance, parental leave for you, your spouse/domestic partner, and children, and a 401k with company match.