Principal Machine Learning Engineer, Communication Safety

Roblox • San Mateo, CA

1d • Onsite

About The Position

Every day, tens of millions of people come to Roblox to explore, create, play, learn, and connect with friends in 3D immersive digital experiences– all created by our global community of developers and creators.
At Roblox, we’re building the tools and platform that empower our community to bring any experience that they can imagine to life. Our vision is to reimagine the way people come together, from anywhere in the world, and on any device. We’re on a mission to connect a billion people with optimism and civility, and looking for amazing talent to help us get there.
A career at Roblox means you’ll be working to shape the future of human interaction, solving unique technical challenges at scale, and helping to create safer, more civil shared experiences for everyone.
Why Safety?
At Roblox, we strive to connect a billion people with optimism and civility, and the Safety organization’s mission is to become the leader in civil immersive online communities. We systematically and proactively detect, remove, and prevent problematic content and behavior. In doing so, we keep Roblox safe, civil, and inclusive, fostering positive relationships between people around the world.
Why Safety AI Systems?
As a Senior/Principal Machine Learning Engineer for Safety AI Systems, you will define the future of proactive moderation, driving immense social impact through cutting-edge, innovative ML solutions. This role is a fusion of a Principal Engineer's technical authority and an Engineering Manager's leadership, focused on the most critical and ambiguous safety challenges.
You will set the 3-5 year technical strategy and architectural blueprint for how Roblox uses machine learning—from high-velocity text filtering to leveraging multimodal Generative AI—to combat the most complex critical harms on the platform. You will own the execution roadmap and technical planning, directly guiding the launch of high-priority new ML projects. You will be responsible for defining the standards of innovation in data quality, model robustness, and ethical deployment across the entire Content & Communication Safety ML pillar.
You will lead and scale a high-performing group of individual contributors, providing both strategic oversight and hands-on guidance to the teams responsible for the architectural development of massive-scale systems that mitigate abuse and harassment before it impacts our community.
You will feel a deep sense of responsibility in proactively protecting our community—thoughtfully and fairly—while balancing user freedom with platform civility. Your efforts will ensure Roblox remains one of the safest places on the internet for users.

Requirements

• 8+ years of experience designing, developing, and operating large-scale, high-impact machine learning systems in a production environment.
• 5+ years of experience in technical leadership, management, or mentorship roles, ideally having managed Engineering Managers or Senior/Principal-level individual contributors.
• A proven track record of successfully setting the long-term technical direction for an entire ML domain or pillar, demonstrating the ability to take ambiguous problems from concept to scaled production impact.
• Deep expertise in advanced ML architectures, including Large Language Models (LLMs), transfer learning, or other foundation model technologies, especially applied to text or multimodal data.
• Expertise in architecting scalable, real-time ML inference services and robust data pipelines operating at millions of requests per second.
• Demonstrated success in leading and resolving high-stakes, cross-functional conflicts and technical disagreements, with an ability to build consensus among diverse stakeholders.
• Exceptional product sense and strategic planning ability: able to translate platform safety requirements into an achievable, iterative technical roadmap.

Nice To Haves

• A Visionary Architect: Capable of synthesizing complex business and safety goals into a clear, compelling, and actionable technical strategy.
• An Inspiring Leader: Passionate about developing the next generation of technical leaders, managers, and engineers.
• Comfortable with Ambiguity: You thrive in undefined or open-ended problem spaces, providing structure, clarity, and decisive direction to your teams.
• An Executive Communicator: Highly effective at communicating complex technical concepts to both engineering teams and non-technical executive leadership.
• Committed to Ethical AI: Dedicated to building ML systems that are fair, transparent, and operate with the utmost responsibility toward user safety and platform civility.

Responsibilities

• Define and Own the Technical Vision: Define and lead the multi-year technical vision, architectural strategy, and execution for machine learning solutions across Content and Communication Safety, ensuring these systems proactively and effectively detect and prevent high-severity, critical harms at massive scale.
• Provide Senior/Principal-Level Architecture: Act as the highest technical authority for the Content Safety ML domain, guiding the architecture and long-term maintainability of foundational models, data pipelines, and real-time inference services.
• Drive Cross-Org Alignment: Identify and champion the most ambiguous, high-leverage technical problems, driving alignment and securing investment for organization-wide ML infrastructure and platform development initiatives that benefit all of Trust & Safety.
• Lead Innovation in Safety: Oversee the adoption and safe deployment of innovative technologies (e.g., advanced NLP, self-supervised learning, multimodal LLMs) to anticipate and mitigate novel abuse vectors, moving beyond reactive detection to proactive intervention.
• Strategic Stakeholder Partnership: Collaborate with executive-level Product, Data Science, Policy, and Operations leaders to define and prioritize the strategic machine learning roadmap, influencing product strategy and demonstrating the impact of ML on user trust and safety outcomes.

What This Job Offers

• Job Type: Full-time
• Career Level: Senior
• Education Level: No Education Listed