Raised in Hampshire, England, Prasanna Puwanarajah was more interested in sports than art when he was growing up. He did some acting as a teenager, but when the time came to attend university, Puwanarajah earned entry to Oxford, where he studied medicine. After graduating, he continued his pursuit of a medical career, but continued acting on the side. Puwanarajah eventually decided to take a year off of medicine to focus on acting, and found enough success that he changed career paths. His first onscreen role came in 2006, when he appeared in a small part on the TV mini-series "The Path to 9/11" (ABC, 2006). His medical training did come in handy, as he played a doctor in recurring roles on the series' "Silk" (BBC One, 2011-14), and "Critical" (Sky 1, 2015), as well as a recurring part on "Doctor Foster" (BBC One, 2015-). In 2018, Puwanarajah was set to appear in a recurring role on the highly anticipated series "Patrick Melrose" (Showtime, 2018-), starring Benedict Cumberbatch in the title role.