Principal Applied Scientist

Ads Fraud Detection sits at the critical intersection of Security and Machine Learning, defending one of the largest advertising ecosystems in the world. We build and operate advanced ML systems that identify and neutralize fraudulent web traffic in real time at massive scale, protecting advertiser ROI, publisher integrity, and user trust. Our mission requires us to push the frontier of high-precision, high-recall detection while adapting continuously to an increasingly sophisticated threat landscape.

As a Principal Applied Scientist on the Microsoft Ads Fraud Detection team, you will lead the most complex and ambiguous fraud challenges: designing new anomaly detection approaches to surface emerging attacks early, building robust cross-signal correlation frameworks to define and expand fraud perimeters, and developing next-generation ML models and low-latency pipelines that stop attacks before they scale. A key expectation for this role is to architect scalable solutions end to end, ensuring detection systems remain performant, resilient, and cost-efficient as data volume, attack complexity, and business demands grow. You will also provide technical leadership across the organization by mentoring other scientists, guiding project direction, and raising the bar on scientific rigor and execution quality. You will also ensure that every solution meets production reliability requirements. Your work will directly influence platform capabilities.

Microsoft's mission is to empower every person and every organization on the planet to achieve more. As employees we come together with a growth mindset, innovate to empower others, and collaborate to realize our shared goals. Each day we build on our values of respect, integrity, and accountability to create a culture of inclusion where everyone can thrive at work and beyond.

Starting January 26, 2026, Microsoft AI (MAI) employees who live within a 50- mile commute of a designated Microsoft office in the U.S. or 25-mile commute of a non-U.S., country-specific location are expected to work from the office at least four days per week. This expectation is subject to local law and may vary by jurisdiction.

• Independently lead and execute multiple high-impact fraud detection initiatives, turning ambiguous problems into measurable business outcomes.
• Develop practical, deployable machine learning (ML) solutions that operate reliably at production scale, balancing detection effectiveness, latency, resilience, operational complexity, and cost.
• Translate scientific insights into production impact through rigorous experimentation, validation, rollout, monitoring, and continuous optimization under real-world operating constraints.
• Apply advanced ML methods-including anomaly detection, cross-signal analysis, large language models (LLMs), and other modern AI techniques-with clear evaluation frameworks, robust tests, and success metrics to deliver reliable, scalable, production-ready solutions.
• Drive technical collaboration across science, engineering, ads, security, and privacy teams to operationalize research and deliver end-to-end fraud detection capabilities.
• Raise the technical bar through mentorship, scientific rigor, responsible AI practices, and high standards for quality, reliability, and governance.

Required Qualifications:

• Bachelor's Degree in Statistics, Econometrics, Computer Science, Electrical or Computer Engineering, or related field ]
• 6+ years related experience (e.g., statistics, predictive analytics, research)
• OR Master's Degree in Statistics, Econometrics, Computer Science, Electrical or Computer Engineering, or related field AND 4+ years related experience (e.g., statistics, predictive analytics, research)
• OR Doctorate in Statistics, Econometrics, Computer Science, Electrical or Computer Engineering, or related field AND 3+ years related experience (e.g., statistics, predictive analytics, research) OR equivalent experience.

Other Requirements:
Ability to meet Microsoft, customer and/or government security screening requirements are required for this role. These requirements include but are not limited to the following specialized security screenings:

• Microsoft Cloud Background Check: This position will be required to pass the Microsoft Cloud background check upon hire/transfer and every two years thereafter.

Preferred Qualifications:

• Master's Degree in Statistics, Econometrics, Computer Science, Electrical or Computer Engineering, or related field AND 9+ years related experience (e.g., statistics, predictive analytics, research) OR Doctorate in Statistics, Econometrics, Computer Science, Electrical or Computer Engineering, or related field AND 6+ years related experience (e.g., statistics, predictive analytics, research) OR equivalent experience. 5+ years experience creating publications (e.g., patents, libraries, peer-reviewed academic papers). 2+ years experience presenting at conferences or other events in the outside research/industry community as an invited speaker. 5+ years experience conducting research as part of a research program (in academic or industry settings). 3+ years experience developing and deploying live production systems, as part of a product team. 3+ years experience developing and deploying products or systems at multiple points in the product cycle from ideation to shipping.
• Extensive industry experience delivering machine learning solutions to production, including technical leadership in complex, ambiguous problem spaces.
• Proven track record architecting scalable ML systems and low-latency decision pipelines that operate reliably and cost-efficiently at web scale.
• Deep expertise in several of the following areas: statistical machine learning, anomaly detection, fraud and risk modeling, deep learning, large-scale data mining, and causal inference.
• Demonstrated ability to set technical direction, influence cross-functional partners, and drive multi-year strategy across research and engineering teams.
• Solid software engineering and system design skills, including model operationalization, experimentation frameworks, and production quality standards.
• Experience mentoring and developing scientists, with a history of raising scientific rigor and execution quality across teams.
• Excellent communication and stakeholder management skills, with the ability to translate complex technical concepts into business impact.
• Research impact through publications, patents, or significant internal innovations in fraud detection, anomaly detection, or related ML domains.

#MicrosoftAI #Fraud #risk #ML #copilot

Applied Sciences IC5 - The typical base pay range for this role across the U.S. is USD $142,800 - $274,800 per year. There is a different range applicable to specific work locations, within the San Francisco Bay area and New York City metropolitan area, and the base pay range for this role in those locations is USD $188,000 - $304,200 per year.

Certain roles may be eligible for benefits and other compensation. Find additional benefits and pay information here:

This position will be open for a minimum of 5 days, with applications accepted on an ongoing basis until the position is filled.

Microsoft is an equal opportunity employer. All qualified applicants will receive consideration for employment without regard to age, ancestry, citizenship, color, family or medical care leave, gender identity or expression, genetic information, immigration status, marital status, medical condition, national origin, physical or mental disability, political affiliation, protected veteran or military status, race, ethnicity, religion, sex (including pregnancy), sexual orientation, or any other characteristic protected by applicable local laws, regulations and ordinances. If you need assistance with religious accommodations and/or a reasonable accommodation due to a disability during the application process, read more about requesting accommodations.