James Nyoro will be sworn-in on Friday after the initial plan to conduct the ceremony on Thursday failed.
Kiambu Speaker Stephen Ndichu had announced the postponement, citing unavoidable circumstances.
The swearing-in was gazetted on Thursday evening.
The swearing-in will take place at 10am at the county headquarters.
The vacancy in the governor's office follows the upholding of Ferdinand Waititu's impeachment by the Senate on Wednesday following three charges, all of which were upheld.
The first charge was gross violation of the Constitution, Public Finance Management Act and PPD Act.
For this charge, 27 senators upheld the charge, while 12 voted in the governor's favour.
In the second charge - crimes under the national law, 28 senators upheld the charge, while 11 voted to drop the charge.
In the third charge - abuse of office - 28 voted to uphold the charge, while 11 voted to drop it.
Waititu becomes the second governor to have the Senate uphold his impeachment.