Principal Software Engineer

The Microsoft Security Defender for Office (MDO) Team delivers cloud-based email and messaging protection that safeguards customers from advanced threats—including malware, phishing, fraud, and spam—across Microsoft email and Teams workloads. MDO also provides powerful investigation, threat hunting, and remediation capabilities, enabling security teams to quickly identify, prioritize, and respond to threats at scale. Security is a top priority at Microsoft, and the Defender for Office team operates at the forefront of this mission. We focus on detecting malicious activity, responding rapidly, and neutralizing threats before they impact customers. We are seeking a Principal Software Engineer to join our Foundations Organization to help build the next generation of services that will power MDO into the future. In this role, you will serve as a security architect and advocate, shaping a secure-by-design platform and driving a security-first mindset across the organization. You will lead architectural decisions, influence culture, and collaborate across geographies and engineering teams to deliver resilient, next-generation security solutions.