A judge finalised the co-guardianship agreement Katherine, 82, and TJ, 34.
The decision finalises an agreement put in place earlier this month after Katherine was removed and then reinstated as the children's permanent guardian, following a family fued.
Katherine was sent to a spa in Arizona and was allegedly unable to reach her grandchildren Prince Michael, Paris and Blanket as her other children fought with the late popstar's estate, the Hollywood Reporter said.
Katherine stated that she supports having TJ as a co-guardian, revealing that she has often relied on his help in raising the three young children.
"I am, and have been, very close with my grandson TJ and have relied on him to help me raise Prince, Paris and Blanket since the death of their father.
"While I was away, I assumed that (the children) would be secure and safe in the hands of the person who had essentially been acting as an informal co-guardian on many matters with me since my appointment as guardian," Katherine said.
She also said that she realizes there are certain instances that would require her nephew to have legal authority over the trio in order to ensure their welfare.
"This realization is the reason I support TJ's continuation as a temporary co-guardian... And to serve alone as guardian if there ever becomes a time that I can no longer serve with him as co-guardian," she said.
Jackson's siblings were at war with his estate executors over King of Pop's USD 500 million fortune and wanted Katherine to come on board to challenge Michael's will and get the executors removed.
