It said the legal move is intended “to deal with the residual noise relating to Mr Moyo contending that he can immediately return to work”.
The appeal is set to be heard on 13 August.
Back and forth
The conflict has been ongoing since May, when Moyo was suspended following a “break down” between him and the board.
On 2 August, Old Mutual confirmed it was heading back to court to block his return.
Delinquent and untenable
According to a company statement, Old Mutual would be depicted as delinquent if it did not appeal against the reinstatement of a chief executive “who had impugned the integrity of the company’s board of directors”.
“The serious allegations made by Mr Moyo has resulted in an untenable working relationship between him and the board.”
The company added that it believed it had made the right decision to terminate Moyo’s employment and was entitled, by law, to do so.
“Old Mutual reiterates that it board can and should hold the chief executive to a high standard, particularly in circumstances where the contract of employment expressly requires a relationships of trust and mutual respect,” the company said.
Adding that it “is confident it will be successful in the current processes before the court”.
The Old Mutual South Africa business split from the group following the managed separation that was first announced in March 2016.
The move saw Nedbank and Old Mutual in South Africa spun out, while the UK wealth management business rebranded as Quilter and the single-strategy arm of Old Mutual Global Investors was sold and renamed Merian.
The South Africa operation has no connection to Quilter or Old Mutual International, which has yet to adopt the group’s branding.