William and Catherine attended the university's fundraising dinner at Middle Temple Hall in London.
William addressed the gathering, telling them how much he and his wife valued their experience at the Scotland university.
"We love it for its traditions, traditions that lie at the very heart of Scotland's history. We love it because it made us look beyond St Andrews, beyond the borders of Scotland, to the wide world," he said, according to the BBC. "But perhaps most important of all, we love it for the friendships it has given us."
"As I look around this hall tonight, and even take a peek at the person sitting three from my left (where Catherine was seated) I thank God for those friendships, our friendship, forged in our ancient halls," he said.
Now both 30 years old, the pair enrolled at St. Andrews in 2001. Before they dated, they were friends at the university for more than a year, and lived as flatmates.
It's believed that the first sparks ignited between the two on March 27, 2002 at a university student fashion show. Catherine - then Kate Middleton - modeled the now-famous see-through dress that reportedly caught William's eye.
Both graduated from St. Andrews in 2005. William earned a geography degree, while Catherine earned a degree in art history.