Principal ML Engineer — Personalization & Matchmaking AI

Riot Games; Los Angeles (CA); On-site; USD 292,000 - 438,000; Full time

Benefits offered by this job

Medical insurance

Dental insurance

Life insurance

Parental leave

401k with company match

Open PTO

Job summary

Riot Games in Los Angeles seeks a Principal Machine Learning Engineer for the Publishing Platform Data team to define modeling architecture powering personalization, matchmaking, and social experiences. You’ll partner with Product, Data Engineering, and Software Engineering to transform large-scale data into fair, player-centric AI systems that shape how players connect and discover communities.

You will mentor senior engineers and set cross-team AI standards.

Qualifications

• 10+ years in ML/Applied AI with 3+ years in principal leadership.
• Experience with large-scale, real-time ML systems.
• Expertise in graph ML, RL, and representation learning.
• Proficiency in PyTorch, TensorFlow, JAX; Ray, Kafka, Flink, Redis.
• Strong AB testing, experiment design, and experience metrics.
• Track record of setting ML strategy across teams.

Responsibilities

• Define and lead modeling architecture for personalization, matchmaking, social graph recommendations, and player/community discovery.
• Architect multi-model systems combining skill, preference, trust, and safety signals.
• Develop models for skill inference, player behavior prediction, trust & safety signals, and multi-objective optimization.
• Build and optimize real-time inference systems for personalized content and matchmaking at global scale.
• Drive adoption of contextual bandits, reinforcement learning, graph ML, and session-aware personalization.
• Partner with Data Engineering and Product to shape data schemas, telemetry standards, and model observability.
• Define Responsible AI standards and implement fairness audits and safety mechanisms.
• Lead post-launch evaluations of algorithmic impact on player sentiment and ecosystem health.
• Set organization-wide standards for model optimization, latency, and drift detection.
• Mentor senior ML engineers and data scientists; influence system design and experimentation strategy.

Skills

ML leadership

Real-time ML systems

Graph ML & RL

PyTorch TensorFlow JAX

Experiment design

ML strategy

Tools

Ray

Kafka

Flink

Redis

Job description

Riot Games in Los Angeles seeks a Principal Machine Learning Engineer for the Publishing Platform Data team to define modeling architecture powering personalization, matchmaking, and social experiences. You’ll partner with Product, Data Engineering, and Software Engineering to transform large-scale data into fair, player-centric AI systems that shape how players connect and discover communities.

You will mentor senior engineers and set cross-team AI standards.