Prime Minister Jacinda Ardern has asked anyone considering a wedding gift to Prince Harry and Meghan Markle to make a donation to charity.

The Government will make a $5000 donation to Pillars, a charity which supports the children of prisoners, the PM said at her post-Cabinet press conference today.

The couple had asked that in lieu of gifts, donations were made to a chosen charity. Ardern said the Government was happy to oblige on behalf of New Zealand.

Pillars New Zealand chief executive Verna McFelin it was wonderful to receive such a generous gift on the eve of the 30th anniversary of the organisation.

More than 23,000 children have a parent in prison and were often affected socially and economically by the changes to their lives, Pillars New Zealand said.

Ardern said Prince Harry and Markle were happy their wedding was being acknowledged in New Zealand through a donation to Pillars.

"The couple are both very interested in initiatives that support vulnerable children and young people."

The couple will wed at St George's Chapel, Windsor Castle, on Saturday. It will be broadcast live, with Kiwis able to tune in on Saturday evening (NZT).