Williams got the better of Azarenka in the final at Flushing Meadows for a second year running after a battle that lasted two hours and 45 minutes, with the veteran forced to dig deep in a dominant deciding set.
The 31-year-old insists that she was pushed to the limit in pursuit of a 17th Grand Slam title, quickly praising her adversary after collecting a fifth US Open title.
She said: "I definitely felt the love to thank you for all who supported. Victoria, you played unbelievable, what a great match, what a great person and what an honour to play against you.
"And to everyone in that box, I love you. Vika is such a great opponent, such a great fighter, it was never over until match point."
Azarenka had battled back from 4-1 down in the second set to level the match, but fell away in the third set as Williams found form to triumph 7-5 6-7(8) 6-1 in New York.