The pair are said to have grinded and grabbed each other as they took to the stage for a TV recording of the 21 year old's hits.
Cyrus's recent suggestive costumes and routines echo those from 55-year-old Madonna's risque performances of her earlier years.
And the pop queen seemed more than happy to dress in a similar sequined cowboy outfit to Cyrus and stick her tongue out in what has become the younger singer's trademark pose.
The musicians sang Cyrus' "We Can't Stop" and Madonna's "Don't Tell Me" in the hour-long acoustic show for an MTV Unplugged programme in the US.
Performing alongside Madonna has become something of a rite of passage or seal of approval for young female pop superstars, following shows in which she has collaborated with the likes of Britney Spears, Christina Aguilera and MIA.
Cyrus' show featured a number of songs from her latest album "Bangerz," including "Wrecking Ball," which was released alongside a controversial video in which she appeared naked.
The performance is being screened in the US tonight and will be broadcast in the UK at a later date.
On Sunday, Madonna performed at the Grammy awards where she took to the stage with 33 couples for a mock mass wedding in support of gay marriage.
(c) Sky News 2014
Original headline: Madonna and Miley Express Themselves For Duet
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