Vonn, still recovering after tearing two knee ligaments in a February ski accident, is quite the one-woman cheering section — she was also on the sidelines at the Masters and US Open.
The high profile couple appear to be stronger than ever and were seen joking around as they walked through the course.
The sports couple went public with their romance in March in a series of corny Facebook photos and have since attended a string of public events, including the Met Ball in May.
As the supportive girlfriend, Vonn took photos, lent support and did everything but carry his clubs. She looked comfortable for the whole round and sat patiently on the side of the 18th green as Woods sank a putt.
Whether on the course or in the water, Vonn also seems to be a hit with Woods and his kids kids, Samantha and Charlie.