Senior Machine Learning Engineer - AdTech
Roku · Cambridge, United Kingdom · 3mo ago
Teamwork makes the stream work.
Roku is changing how the world watches TV
Roku is the #1 TV streaming platform in the U.S., Canada, and Mexico, and we've set our sights on powering every television in the world. Roku pioneered streaming to the TV. Our mission is to be the TV streaming platform that connects the entire TV ecosystem. We connect consumers to the content they love, enable content publishers to build and monetize large audiences, and provide advertisers unique capabilities to engage consumers.
From your first day at Roku, you'll make a valuable - and valued - contribution. We're a fast-growing public company where no one is a bystander. We offer you the opportunity to delight millions of TV streamers around the world while gaining meaningful experience across a variety of disciplines.
What does the team work on?
Roku is the No. 1 TV streaming platform in the U.S., Canada, and Mexico with 70+ million active accounts. Roku pioneered streaming to the TV and continues to innovate and lead the industry. Roku enables our users to access millions of pieces of content — movies, episodes, news, sports, music, and channels — from all around the world, and our advertising systems connect advertisers to that audience at scale.
What is the role?
You’ll join Praveen Krishnaiah’s Native Ads Modelling team building the ML systems behind ad relevance, bid and yield optimization, and real-time, low-latency ad serving. This is a senior, hands-on ML engineering role spanning modelling, large-scale training, and production infrastructure — you’ll take models from idea through to serving at scale, working in Spark, Python, and Java. You’ll work closely with Praveen and the wider Ad Performance ML team. Based in the UK (Manchester-anchored).
How will I use AI at Roku?
At Roku, we don’t just use AI, we work with it. AI agents and smart tools help power drafts, analysis, and repetitive workflows, while our people bring direction, judgment, and accountability. We’re looking for curious, adaptable builders who can show how they’ve used AI or automation to move faster, raise the bar, and scale their impact.
We value your AI skills if you have built fluency across the agentic engineering toolchain — coding harnesses like Claude Code or Cursor, MCP servers, custom skills, or agent frameworks — and can describe projects where you shipped real work with these tools. You know how to drive an agent, verify its output, and ramp on an unfamiliar codebase with an agent helping you.
What are the responsibilities of the role?
- Design, train, and ship ML models for ad relevance and bid/yield optimization
- Build and maintain production ML infrastructure for real-time, low-latency serving
- Work across Spark, Python, and Java to move models from research to production
- Apply sound feature engineering, validation, and evaluation practices throughout the modelling lifecycle
- Diagnose production ML issues such as model drift or long-tail classification problems
- Communicate technical trade-offs clearly to engineering and cross-functional partners
What experience would help someone be successful in this role at Roku?
- Senior-level ML engineering experience, ideally with exposure to ad tech, recommendation, or auction systems
- Strong grounding in ML fundamentals, feature engineering, and model evaluation
- Experience with Spark, Python, and Java in production ML settings
- Comfort with production ML infrastructure and real-time, low-latency serving requirements
- Demonstrated AI/agentic-tooling fluency per the section above
- Clear communicator who can explain reasoning and trade-offs, not just conclusions
#LI-MS3
What's Roku's approach to hybrid working?
Roku fosters an inclusive and collaborative environment where teams generally work in the office Monday through Thursday. Fridays are generally flexible for remote work, except for employees whose specific roles or assigned office location require five days' a week attendance.
What are some of the benefits?
Roku is committed to offering a diverse range of benefits as part of our compensation package to support our employees and their families. Our comprehensive benefits include global access to mental health and financial wellness support and resources. Local benefits include statutory and voluntary benefits which may include healthcare (medical, dental, and vision), life, accident, disability, commuter, and retirement options (401(k)/pension). Employees are supported in taking time off, in accordance with local leave policies and other personal needs to support their evolving work and life needs. It's important to note that not every benefit is available in all locations or for every role. For details specific to your location, please consult with your recruiter.
Accommodations
Roku welcomes applicants of all backgrounds and provides reasonable accommodations and adjustments in accordance with applicable law. If you require reasonable accommodation at any point in the hiring process, please direct your inquiries to EmployeeRelations@Roku.com.
What should I know about Roku's culture?
Roku is a great place for people who want to work in a fast-paced environment where everyone is focused on the company's success rather than their own. We try to surround ourselves with people who are great at their jobs, who are easy to work with, and who keep their egos in check. We appreciate a sense of humor. We believe a fewer number of very talented folks can do more for less cost than a larger number of less talented teams. We're independent thinkers with big ideas who act boldly, move fast and accomplish extraordinary things through collaboration and trust. In short, at Roku you'll be part of a company that's changing how the world watches TV.
We have a unique culture that we are proud of. We think of ourselves primarily as problem-solvers, which itself is a two-part idea. We come up with the solution, but the solution isn't real until it is built and delivered to the customer. That penchant for action gives us a pragmatic approach to innovation, one that has served us well since 2002.
To learn more about Roku, our global footprint, and how we've grown, visit https://www.weareroku.com/factsheet.
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