An impressive fortnight in New York ended in disappointment for Wozniacki, who was quick to heap praise on her rival and off-court friend following a 6-3 6-3 triumph for the top seed.
"You really deserved it today, you played better than me," the Dane admitted as she addressed Williams after the match. "You're an unbelievable champion, an inspiration to me on and off court.
"You're an unbelievable friend and you definitely owe me drinks later."
Wozniacki's search for a first Grand Slam victory goes on following a second defeat in a US Open final.