Stevens will become managing director of the group's new commercial division.
He will oversee marketing, sales and Arla's relationship with advertising agency Clemmow Hornby Inge.
Previous head of marketing Hanne Sondergaard will no longer have a marketing role, but will retain the position of executive director of Arla Foods UK. She will also remain on the board.
Arla Amber, which owns 51% of Arla UK, has been divided into four units: Consumer Nordic, Consumer UK, Consumer International and Global Ingredients.
The restructure comes two months after Peder Tuborgh was appointed managing director of Arla Amber.
The Consumer UK division, which is to be headed by Kim Nielsen, will incorporate Arla Foods UK.