The phrase "acknowledged officially" is correct and usable in written English.
You can use it when referring to something that has been recognized or accepted by an authoritative body or in a formal context.
Example: "The committee's decision was acknowledged officially in the meeting minutes."
Alternatives: "formally recognized" or "officially accepted".
In February, top universities issued guidance which acknowledged officially for the first time that they favoured traditional subjects over vocational ones, such as law.
"The Biak massacre is widely known in anecdotal terms in West Papua as being a really severe event but it's not acknowledged officially at all – certainly not by the Indonesian government," he said.
His cautionary comments were the first time anyone in the administration had acknowledged officially that it was acceding to a request by Prime Minister Ariel Sharon to delay completion of the "road map" proposal, which is actually a seven-page document being drafted by the United States, the European Union, Russia and the United Nations.
Although rarely acknowledged officially, the Chinese government does occasionally take part in talks with Tibet's government-in-exile, based in India.
The United States never acknowledged officially participating in a war in Laos, and Laos was not a party to the Paris accord.
But the auto maker declined to acknowledge officially that shutdowns at those factories were likely.
Top universities will today issue guidance which acknowledges officially for the first time that they favour students who study traditional subjects at A-level.
There is a chance, however, that Texas could become the first state to acknowledge officially that, since the advent of the modern judicial system, it had carried out the "execution of a legally and factually innocent person".
One day a year, the children of working parents are publicly acknowledged and officially welcomed in the workplace with activities, speakers and sometimes a boxed lunch.
The architectural antiquity of much of Hermann is formally & officially acknowledged.
President Jacques Chirac first officially acknowledged France's "collective wrongdoing" during the Vichy years in 1995.
