The company had said in June that CEO Stefan Heidenreich, 55, would step down when at the end of 2019 or earlier, depending on when a successor was selected.
At that time, De Loecker, 51, was named deputy CEO and commissioned with the development of Beiersdorf's strategy.
Beiersdorf declined to comment on the manager magazin article.
Heidenreich took over as CEO in April 2012 at a time when Beiersdorf was losing market share to rivals such as L'Oreal and profit margins were falling.
Under his leadership the group has regained market share, introduced a new Nivea logo as part of his Blue Agenda strategy, focussed on emerging markets and stripped out underperforming product lines.
De Loecker, a Belgian, presented the first results of his strategy plan to the supervisory board this month, the magazine said. He is to be named Heidenreich's successor before the Christmas holidays, it said.
(Reporting by Jan Schwartz; writing by Riham Alkousaa; editing by Jason Neely)