The former Baywatch star has been desperate to wed his Welsh girlfriend Hayley Roberts ever since they started dating early last year (11).
Hasselhoff has previously dropped to his knee and asked the blonde to marry him on five different occasions, but she has so far turned down his proposals.
However, it now appears the actor has finally got the answer he wanted after popping the question at the top of the famous Australian landmark.
He posted a picture of the pair at the top of the bridge on his Twitter.com page along with the words, "Tried it again on top of the Sydney Harbour Bridge!" adding, "What do you think she said!?!?!" before posting a picture of them embracing in a passionate kiss.
Roberts also kept fans guessing as she suggestively put up a smiley face with lots of kisses on her own Twitter blog.
Hasselhoff has been married twice before to Catherine Hickland and Pamela Bach, the mother of his two grown-up daughters.