It is said the couple let their first nanny go, while the second only worked nights.
The baby royal arrived on May 6 and has been rarely seen in public since.
The Duchess of Sussex is said to have described the newest member of the team as a 'godsend' and a perfect fit for the family.
She accompanied Meghan, 38, Harry and Archie on their private jet holiday to Elton John's home in Nice, France, earlier this month.
A royal insider told The Sun, "Meghan is a very hands-on mum but the new nanny is a godsend. She is extremely professional, with a number of nannying years under her belt, and has fitted into the family really well. She’s great with little Archie. Harry and Meghan are very happy with her.”
The new nanny will join the royal couple on their trip to Africa next month.
The Sussexes have recently gone on a hiring spree, employing a housekeeper at their Frogmore Cottage home, in Windsor, and a new private secretary.
It comes after a string of high-profile departures from the Sussex's team.
Meghan's former private secretary Samantha Cohen quit her role after six months, bringing an end to her 17-year stint with the royals. She has now been replaced by the former ambassador Fiona Mcilwham.
The Duchess's former bodyguard also quit after around six months work.
The actress's old personal assistant Melissa Touabti left six months after the royal wedding, reportedly due to the heavy demands placed on her.