Principal Machine Learning Engineer

Hims & Hers is the leading health and wellness platform, on a mission to help the world feel great through the power of better health. We are redefining healthcare by putting the customer first and delivering access to care that is affordable, accessible, and personal, from diagnosis to treatment to delivery. As Principal Machine Learning Engineer, you will define and drive the architectural vision for large-scale, foundational machine learning models and applications that power care personalization, treatment intelligence, and automation at scale. Your work will directly impact every aspect of patient care, including MedMatch, our AI-powered system that enhances provider-patient interactions, optimizes treatment recommendations, and expands into new verticals. Responsibilities: Define and drive the architectural vision for ML and LLM systems that support treatment recommendation, personalization, and intelligent care delivery at scale Establish foundational design patterns and infrastructure practices that ensure systems are scalable, resilient, secure, and maintainable Work hands-on with Python and ML frameworks like PyTorch to prototype, optimize, and guide implementation of complex model pipelines and platform components Align high-impact technical decisions with long-term product strategy by partnering with platform, product, and clinical teams Architect and evolve robust ML infrastructure to support continuous training, real-time inference, evaluation, and observability Lead cross-functional initiatives that simplify system complexity, improve developer velocity, and increase organizational leverage Shape quality strategies across teams by defining standards for testing, observability, performance, and operational risk Mentor senior and staff engineers across squads, supporting their growth as systems thinkers and technical leaders Champion a culture of sustainable speed, system ownership, and architectural clarity across product and platform teams Requirements: 10+ years of experience in Machine Learning and/or Engineering, with a strong track record of technical leadership and system architecture across teams or business areas Expert-level proficiency in Python and advanced ML frameworks such as PyTorch or TensorFlow Demonstrated success in designing, scaling, and evolving ML platforms that support production-grade training, deployment, real-time inference, and monitoring Deep experience in LLMs and NLP, including transformer models, summarization, conversational agents, and embedding-based retrieval Advanced understanding of ML infrastructure, including continuous training, system observability, performance optimization, and platform reliability Experience with ML infrastructure tools such as Databricks, MLFlow, SageMaker, or equivalent A Master’s degree or PhD in Computer Science, Machine Learning, or a related field (not strictly required) Exceptional communication and cross-org leadership skills, with the ability to align diverse technical and non-technical stakeholders around ML strategy and long-term architecture Benefits: Competitive salary & equity compensation for full-time roles Unlimited PTO, company holidays, and quarterly mental health days Comprehensive health benefits including medical, dental & vision, and parental leave Employee Stock Purchase Program (ESPP) 401k benefits with employer matching contribution Offsite team retreats Job Data by YubHub .