[2026] Senior Machine Learning Engineer, Recommendation Systems PhD Early Career

Recommendation Systems are a key growth lever at Roblox driving retention engagement and monetization for hundreds of millions of users. This role offers the unique opportunity to redefine how users search and discover everything from the most interesting immersive experiences and digital avatars in our Marketplace to personalized advertising. You will solve a diverse range of high-scale ranking retrieval and personalization problems across our platform.

We combine cutting-edge research including deep learning generative AI and reinforcement learning techniques with large-scale engineering to bridge experimentation and production; youll design algorithms that operate at massive scale and shape the next generation of recommender systems for user-generated content.

Teams Hiring for This Role

• Discovery: powers major search and recommendation surfacesdrives user engagement by redesigning core surfaces and search/homepage ranking
• Economy: builds the ML backbone for marketplace monetization and commerce (including fraud pricing and bundling)
• Ads & Brands: focuses on ranking retrieval and marketplace/auction theory to optimize sponsored content delivery.
• Safety Critical Harms: focuses on proactively identifying and mitigating extremely high-risk sensitive content and behaviors using investigative multi-step reasoning behavior analysis and knowledge graphs for risk forecasting.

You Will

• Design and implement large-scale recommendation systems that power discovery across Robloxs surfaces experiences avatars and creator content.
• Develop deep learning models for ranking retrieval and personalization using approaches in multimodal models LLMs and generative AI.
• Collaborate with applied researchers engineers and product teams to advance experimentation and accelerate innovation.
• Translate research into production systems that impact hundreds of millions of daily active users.
• Work backward from user and product needs to deliver ML solutions that drive engagement retention and ecosystem growth.

You Have

• Possessing or pursuing a PhD in computer science engineering or a related field with a thesis aligned to Robloxs research areas.
• Expertise in one or more areas: recommender systems search systems information retrieval or generative models (e.g. LLMs VLMs VLAs)
• Ability to design and architect systems for efficient personalization and user interest modeling using advanced attention mechanisms (e.g. sparse/linear attention).
• A strong research track record evidenced by multiple publications and presentations in top-tier peer-reviewed venues (e.g. SIGIR KDD RecSys ICLR ICML NeurIPS)
• Proficiency in one or more programming languages (e.g. Python C Go Java) and experience building and optimizing large-scale systems.

Apply now to be considered for anticipated positions.

You may redact age date of birth and dates of attendance/graduation from your resume if you prefer.

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Required Experience:

Senior IC