The track, which is lifted from his latest album Love In The Future, also marks his first ever top 40 hit on the ARIA chart.
Read Digital Spy's interview with John Legend
Legend previously told Digital Spy that the song is about his fiancée Chrissy Teigen, adding: "'All Of Me' is really specifically about us and her. She's well aware of that. The first time I sang it to her she cried."
Meanwhile, Eminem and Rihanna fall one to two with 'The Monster', Magic! climb from seven to three with 'Rude', and Taylor Henderson rebounds from 12 to ten with 'Borrow My Heart'.
Outside the top ten, Avicii vaults from 41 to 18 with 'Addicted To You', Jason Derulo is new at 22 with 'Trumpets', and Vance Joy's 'Riptide' lifts from 38 to 23.
The Vamps rise from 47 to 34 with 'Can We Dance', Lorde's 'Team' moves from 49 to 39, and MKTO's 'God Only Knows' bows at 45.
Watch the video for Legend's 'All Of Me' below: