Staff Machine Learning Engineer – Ads Bidding

About This Opportunity

Our talent team is representing a confidential London-based marketplace technology company in their search for a Staff Machine Learning Engineer focused on ads bidding systems. This is a rare opportunity to solve genuinely open problems in marketplace advertising at significant scale.

The role sits within a machine learning team building bidding and auction systems that connect consumers with relevant advertising while helping merchants grow revenue through the platform. You'll be working on a migration from cost-per-click to cost-per-order models—a cutting-edge challenge with no established playbook that very few companies have successfully navigated.

Responsibilities

• Own the design and execution of the CPC-to-CPO migration, including determining whether the system remains CPO-facing externally while optimising CPC internally, or adopts a hybrid approach
• Build and improve the bidding surface including goal-based automated bidding, Target CPO, optimised CPC, and Target ROAS systems
• Own yield management tied to return-on-spend targeting
• Partner with cross-functional stakeholders across product, commercial, and engineering teams
• Set technical direction for the ads bidding domain in an ambiguous, rapidly evolving space
• Collaborate with distributed teams across time zones while maintaining reasonable working hours

What We're Looking For

• Deep expertise in ad economics, marketplace bidding systems, or auction theory
• Direct hands-on experience building and shipping optimised CPC, target CPO, goal-based automated bidding, and target ROAS systems in production
• 7+ years writing production code in Python with strong fundamentals in machine learning, ranking, recommendation systems, or bidding/auction mechanisms
• Strong self-driven leadership—you'll be setting direction in ambiguous territory, not following an established roadmap
• A bias toward simplicity and pragmatism with a focus on shipping measurable business impact
• Excellent cross-functional communication skills for partnering with product, commercial, and technical stakeholders
• Experience working in fast-moving, high-ownership environments where you can ship, test, and iterate quickly

How We Work With You

When you apply through Get A Job.ai, one of our specialist recruiters will review your background and conduct an initial screening conversation. If there's a strong match, we'll submit your profile to our client for consideration. Please do not contact the client directly—all communication and interview coordination will flow through our team to ensure the best possible candidate experience.

Location & Working Arrangement

This position is based in London at our client's headquarters office. The role offers flexible working arrangements within a low-hierarchy, high-ownership culture built for builders and problem solvers.

Pay

Compensation details will be discussed during the screening process and are competitive for Staff-level Machine Learning Engineering roles in the London market. Our client offers both competitive salary and equity participation.

Equal Opportunity

Get A Job.ai is committed to inclusive recruiting practices. We welcome candidates from all backgrounds and work with clients who share our commitment to diversity, equity, and workplace inclusion. If you require reasonable adjustments during the recruitment process, please let our team know when you apply.