Labour currently does not have a party base in Auckland other than its MPs' electorate offices.
Little said he would be spending a lot of time in Auckland and needed a base there. It would be formally announced at a Labour function for Auckland businesses, interest groups and movers and shakers on Wednesday.
Auckland was McCarten's stomping ground before he moved to Wellington in 2014 to become former Labour leader David Cunliffe's chief of staff. McCarten was retained by Little after he took over the leadership after the 2014 election.
That will leave Little without a chief of staff in the Parliamentary offices. He would not say what his plans were to fill that position.
Little is also yet to replace his former chief press secretary Sarah Stuart who left in May after little more than a year in the role.
In the past McCarten, a former Alliance Party President, has been involved with the Maori Party and the Mana Party as an advisor.