Senior Lead Machine Learning Engineer

Upwork ($UPWK) is the world’s human and AI-powered work marketplace that connects businesses with highly skilled, AI-enabled independent talent from across the globe. From entrepreneurs to Fortune 100 enterprises, companies rely on Upwork’s trusted platform and its mindful AI companion, Uma, to find and hire expert talent, leverage AI-powered work solutions, and drive business transformation. With on-demand access to professionals spanning more than 10,000 skills across AI & machine learning, software development, sales & marketing, customer support, finance & accounting, and more, Upwork enables businesses of all sizes to scale, innovate, and build agile teams for the age of AI and beyond.

Upwork’s platform has facilitated more than $25 billion in economic opportunity for talent around the world. Learn more at Upwork.com and follow us on LinkedIn, Facebook, Instagram, TikTok, and X.

We’re seeking a Senior Lead Machine Learning Engineer to play a pivotal role in shaping the future of AI-powered intelligence at Upwork. In this high-impact role, you’ll lead the design and delivery of infrastructure and models that support agentic LLM workflows across our platform. Your work will span from research to production, empowering teams and driving innovation that delivers measurable business results.

This is more than a technical leadership role—it’s an opportunity to guide strategy, mentor others, and represent Upwork in the broader AI/ML community. You’ll architect scalable ML systems, guide cross-functional initiatives, and help define the next generation of autonomous AI agents.

Responsibilities

• Design and implement resilient infrastructure for agentic LLM systems, including multi-agent coordination, Retrieval-Augmented Generation (RAG), and real-time orchestration.
• Lead training and fine-tuning of large-scale foundation models tailored to Upwork’s domain-specific challenges and user base.
• Partner with engineering, product, and research teams to align technical development with strategic business priorities.
• Mentor and support other engineers and researchers to elevate team-wide technical capabilities and foster a culture of innovation and inclusion.
• Drive experimentation and translate findings into robust, scalable production systems with clear metrics of success.
• Identify opportunities for innovation, challenge conventional approaches, and lead initiatives that push the boundaries of applied ML.
• Contribute to the external AI/ML community through papers, talks, or open-source contributions, enhancing Upwork’s visibility in the field.

What it takes to catch our eye

• Demonstrated expertise in building, deploying, and scaling advanced ML models in a production environment using Python and frameworks like PyTorch or TensorFlow.
• Deep technical understanding of transformer-based models, generative AI, and agent architectures such as MCP or A2A.
• Proven experience training and optimizing large models on GPU clusters and integrating LLMs with APIs or orchestration systems.
• Track record of leading high-impact, cross-functional initiatives with a focus on business outcomes and customer value.
• A collaborative mindset, clear communication skills, and a drive to mentor and elevate those around you.

Come change how the world works.

At Upwork, you’ll shape the future of work for a global, remote-first workforce, creating economic opportunities for professionals worldwide. While we have a physical office in Palo Alto, we currently hire full-time employees in 34 U.S. states, making it easier than ever to join our mission from wherever you call home.

Our culture is built on trust, risk-taking, customer focus, and excellence, all in service of our core mission: to create economic opportunities so people have better lives. We embrace authenticity and inclusion, encouraging everyone to bring their whole selves to work. Personal and professional growth is a priority here, supported through development programs, mentorship, and our Upwork Belonging Communities.

We’re proud to offer benefits that go beyond the basics, including comprehensive medical coverage for you and your family, unlimited PTO, a 401(k) plan with matching, 12 weeks of paid parental leave, and an Employee Stock Purchase Plan. Visit our Life at Upwork page to learn more about our values, working principles, and the overall employee experience.

Ready to help shape the future of work? Check out our Careers page to learn more about opportunities at Upwork.

Upwork is an Equal Opportunity Employer committed to recruiting and retaining a diverse and inclusive workforce. We do not discriminate based on race, religion, color, national origin, gender (including pregnancy, childbirth, or related medical conditions), sexual orientation, gender identity, gender expression, age, status as a protected veteran, status as an individual with a disability, genetic information, or other legally protected characteristics under federal, state, or local law.

Please note that a criminal background check may be required once a conditional job offer is made. Qualified applicants with arrest or conviction records will be considered in accordance with applicable law, including the California Fair Chance Act and local Fair Chance ordinances.