Senior Process Engineer, Oncology

A Rare Opportunity to Shape the Future of Genomics

Join a team of brilliant, passionate innovators determined to transform healthcare. At BillionToOne, we've built a category-defining, publicly traded company on Nasdaq where transparency fuels trust, collaboration drives breakthroughs, and every contribution moves the needle on our mission to make life-changing diagnostics accessible to all. We don't just aim for incremental improvements; we build products that are 10x better than anything that exists today.

Our scientists, engineers, sales executives, and visionaries are united by an unwavering commitment to changing the standard of care in prenatal and cancer diagnostics. This is where cutting-edge science meets human compassion, and every innovation you contribute helps remove the fear of the unknown from some of life's most critical medical moments.

If you're driven by purpose, energized by innovation, and ready to help shape the future of precision medicine at scale, this is where you belong.

We are looking for a Senior Process Engineer to join our growing superstar Process Engineering team in support of clinical patient testing in our high throughput CLIA lab. The Senior Process Engineer is responsible for (1) Leading the exploration of new technologies which can enable rapid scaling of our commercial assays, (2) Developing and validating new chemistry and/or process changes to enhance product performance, (3) Building out FDA/GMP/ISO compliant Scale-up, V&V, and tech transfer procedures, and (4) Serving as a mentor for junior engineers on the team. This role will enable an individual to flex their skills in process engineering, high-throughput laboratory scaleup, process improvement, statistical analysis, experimental design, and data science (amongst many more). This role will help to build upon the strong technology and execution found within BTO’s walls. The Senior Process Engineer is an onsite position at our Menlo Park location.

Responsibilities:

Source and evaluate external technologies which might benefit COGS, process throughput, assay performance, turnaround time, or other key operational metrics.

Develop the strategies to support 2-3X annual growth in commercial volume.

Build upon the existing statistical Process Control system to enable ever decreasing failure rates and ever increasing assay performance.

Mentor junior engineers and help to establish strong skills and industry best practices across the growing PE team.

Facilitate technology transfer between R&D and the clinical laboratory, identifying CPPs, process tolerances, and failure modes while ensuring that new workflows are proplery implemented in the production environment.

Work with Bioinformatics and Data Science to translate assay CQAs into impactful and actionable process monitoring tools.

Develop new data and information handling tools to aid in efficient sample processing and process monitoring within the clinical laboratory.

Apply six sigma, Design-for-quality, and 5S frameworks to existing or new processes to improve both capability, scalability, and quality of molecular diagnostic assays.

Lead thorough root cause analyses to identify and solve process issues, with a mindset for long-term solutions.

Qualifications:

Bachelor’s, Master’s or Ph.D. in biology, bioengineering, or related sciences

At least 5-6 years of experience with molecular biology techniques in a research or clinical laboratory

Proficiency in R, Python, or an adjacent coding language

Strong statistical analysis skills

Strong experience designing rigorous, well controlled studies in a molecular biology environment

Experience with data presentation and technical report authoring

Experience working with GMP, ISO, or equivalent environments, with strong knowledge of Quality Management Systems and practices.

Excellent attention to detail

Effective written and verbal communication skills

Experience mentoring junior team members

Possess logical troubleshooting skills

Nice-To-Haves:

Start-up experience

Knowledge of medical genetics

Experience in a cell-free DNA setting

Experience with 6-sigma, Lean, JIT, TPS

Experience with CLIA/CAP, 510K, PMA, and other regulatory requirements

Experience with automation or clinical laboratory experience is a bonus

Benefits And Perks:

Working alongside brilliant, kind, passionate and dedicated colleagues, in an empowering environment, toward a global vision, striving for a future in which transformative molecular diagnostics can help millions of patients

Open, transparent culture that includes weekly Town Hall meetings

The ability to indirectly or directly change the lives of hundreds of thousand patients

Multiple medical benefit options; employee premiums paid 100% of select plans, dependents covered up to 80%

Extremely generous Family Bonding Leave for eligible employees (16 weeks, paid at 100%)

Supplemental fertility benefits coverage

Retirement savings program including a 4% Company match

Increase paid time off with increased tenure

Latest and greatest hardware (laptop, lab equipment, facilities)

Free daily on-site lunches provided from top eateries

A variety of perks on campus (state of the art gym, restaurant)

Free on-site EV charging (compatible with all EVs, including Tesla)

At BillionToOne, we are proud to offer a combination of a (1) base pay range (actual amount offered is based on experience and salary/equity options split that the candidate chooses), (2) generous equity options offering, (3) corporate bonus program, on top of (4) industry leading company benefits (free healthcare options, 401k match, very generous fully paid parental leave, etc.).

For this position, we offer a total compensation package of up to $205,064 per year, including a base pay range of $128,622 - $150,058 per year.

BillionToOne is an equal opportunity employer. We do not discriminate on the basis of race, religion, color, national origin, gender, sexual orientation, age, marital status, veteran status, or disability status.

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BillionToOne is a next-generation molecular diagnostics company on a mission to make powerful, accurate diagnostic tests accessible to everyone. Our revolutionary QCT molecular counting technology enhances disease detection resolution by over a thousandfold using cell-free DNA,a breakthrough that has already transformed the lives of over half a million patients worldwide.

Our Impact

Unity Complete™ is the only non-invasive prenatal screen capable of assessing fetal risk for both common recessive conditions and aneuploidies from a single maternal blood sample. Unity Confirm™ enables non-invasive confirmation for high-risk screening results through the capture of intact circulating fetal cells using BillionToOne’s Fetal Cell Capture™ Technology. Our Northstar® liquid biopsy test uniquely combines treatment selection with real-time monitoring, giving oncologists unprecedented precision in cancer care.

Our Growth

From $0 to $400M+ annualized revenue run-rate in just 6 years. In 2025, we completed one of the most successful IPOs for a medical diagnostics company, building on nearly $400M in private funding,including our $130M Series D in 2024 and backed by world-class investors including Hummingbird, Adams Street Partners, Neuberger Berman, Baillie Gifford, and Premji Invest.

Our Recognition

Forbes named us one of America's Best Startup Employers for 2025 and we're Great Place to Work certified , with 100% of our people willing to go the extra mile, even as we've scaled to over 700 employees.

Our Future

Headquartered in Menlo Park with facilities in Union City, CA, and a new lab opening in Austin, TX in 2027, we're continuing to push the boundaries of what's possible in molecular diagnostics. We're just getting started.

Ready to help us change the world, one molecule at a time? Learn more at billiontoone.com