Sr. Principal Machine Learning Engineer - Central Product Insights

Riot has petabytes of data and state-of-the-art processing technologies to build products that elevate the player experience at a massive scale.

As a Sr. Principal ML Engineer within the Central Product team, you will define and drive the modeling architecture that powers personalization, matchmaking, and social experiences across the player ecosystem - in and around the game.Working alongside Product Leaders, Software Engineers & Data Engineers who lead foundational data systems for social graph, presence, chat, and matchmaking telemetry, you will lead the AI and modeling layer that transforms this data into intelligent, adaptive, and fair experiences for our players.

Your work ensures that every player connection - from friend recommendations to lobby matchmaking and in-game social features - feels meaningful, fair, and personalized through responsible, scalable machine learning systems.

Responsibilities:

• Modeling Architecture for Player Intelligence Graph
• Define and lead the modeling architecture that powers player personalization, matchmaking, social graph recommendations, and community discovery.
• Develop models for churn model, revival models.
• Drive multi-objective optimization frameworks balancing fairness, latency, diversity, and experience quality.
• Establish and standardize evaluation protocols (match quality, satisfaction metrics, toxicity mitigation).

Required Qualifications:

• 15+ years in Machine Learning or Applied AI; 3+ years in a principal or staff-level technical leadership role.
• Proven experience in real-time, large-scale ML systems - matchmaking, recommendations, or personalization.
• Deep expertise in graph ML, reinforcement learning, and representation learning.
• Proficiency in PyTorch, TensorFlow, JAX, and modern data/serving frameworks (Ray, Kafka, Flink, Redis).
• Strong understanding of A/B testing, experiment design, and player experience metrics.
• Track record of defining cross-team ML standards and leading technical direction.

Desired Qualifications:

• Background in game development, player behavior modeling, or social ecosystems.
• Experience in trust & safety, toxicity detection, or community health models.
• Familiarity with Vertex AI, SageMaker, or internal orchestration systems for real-time inference.
• Demonstrated success integrating ML systems with live-service game backends.

For this role, you'll find success through craft expertise, a collaborative spirit, and decision-making that prioritizes the delight of players. We will be looking at your past studies, experience, and your personal relationship with games. If you embody player empathy and care about players' experiences, this could be your role!

Our Perks:

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. Check out our benefits pages for more information.

At Riot Games, we put players first. That mission drives every decision in our quest to create games and experiences that make it better to be a player. Whether you’re working directly on a new player-facing experience or you’re supporting the company as a whole, everyone at Riot is part of our mission. And just like in our games, we’re better when we work together. Our goal is to create collaborative teams where you are empowered to bring your unique perspective everyday. If that sounds like the kind of place you want to work, we’re looking forward to your application.

It’s our policy to provide equal employment opportunity for all applicants and members of Riot Games, Inc. Riot Games makes reasonable accommodations for handicapped and disabled Rioters and does not unlawfully discriminate on the basis of race, color, religion, sex, sexual orientation, gender identity or expression, national origin, age, handicap, veteran status, marital status, criminal history, or any other category protected by applicable federal and state law. We consider for employment all qualified applicants, including those with criminal histories, in a manner consistent with applicable federal, state and local law, including the California Fair Chance Act, the City of Los Angeles Fair Chance Initiative for Hiring Ordinance, the Los Angeles County Fair Chance Ordinance for Employers, the San Francisco Fair Chance Ordinance, and the Washington Fair Chance Act.

Per the Los Angeles County Fair Chance Ordinance, the following core duties may create a basis for disqualifying candidates with relevant criminal histories:

• Safeguarding confidential and sensitive Company data
• Communication with others, including Rioters and third parties such as vendors, and/or players, including minors
• Accessing Company assets, secure digital systems, and networks
• Ensuring a safe interactive environment for players and other Rioters

These duties are directly related to essential operations, safety, trust, and compliance obligations within our organization. Please note that job duties may evolve based on business needs and additional responsibilities may be assigned as necessary to maintain operational efficiency and security.