Business by LA Times Studios presents a list of Southern California life science firms ranked by the number of employees in Southern California, including Ventura, Los Angeles, Orange, San Bernardino, Riverside and San Diego counties. Life science companies span a diverse group of organizations that include pharmaceutical developers, medical device manufacturers, biotech companies, contract research and manufacturing companies and diagnostic firms. Data for the list was provided by representatives of the companies themselves and corporate annual reports.
Biotech giant Amgen is the largest company by headcount in Southern California, with 5,000 employees working at its Thousand Oaks campus. Its total revenue increased by 10% in 2025 to $36.75 billion. The gains were widespread with 13 products delivering double-digit percentage sales growth and 14 products achieving sales greater than $1 billion. Its total research and development budget increased to $7.2 billion last year.
Overall, the 25 largest life science employers in Southern California have nearly 30,000 employees combined.
