The pair is set to marry this summer and Harry will put his $40 million fortune on the line.
A source has revealed: "There was never any question in Harry's mind that he would sign a prenup.
"He's determined that his marriage will be a lasting one, so there's no need for him to sign anything.'
This will be the first wedding for Prince Harry, 33, but the second for Markle, 36.
The American actress divorced her first husband, American film producer Trevor Engelson, after two years.
And this prompted many Royal insiders to advise Harry to get a financial arrangement in place before he ties the knot.
But it seems that he is ignoring this advice because he believes that their marriage will be for life.
Prenups are not legally enforceable in the UK, but are increasingly taken into account during divorce cases.
Harry was handed $13 million of the inheritance from his mother, Princess Diana, when he turned 30. He is said to have another $26 million of assets.
Meghan, 36, has amassed an estimated $5.2 million fortune from her successful acting career.
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