Alexander replaces Anthony Fry, who was taken ill earlier this year and has now left the company.
Richard Macdonald, who had been acting chairman during Fry’s illness, will resume his role as senior independent director.
Mark Allen, ceo of Dairy Crest, said: “It is sad that Fry will no longer chair the board. He has had a significant influence on the business since his appointment as a non-executive director in 2007, and especially since he became chairman in 2010. I shall miss working with him."
Alexander joined the UK-owned dairy foods company as a non-executive director in 2011.
He has also chaired the remuneration committee since May 2012.
‘Very strong’
He had been a “very strong non-executive” and made an excellent replacement, Allen said.
Alexander said he was “delighted” with the role.
“Dairy Crest is a good business and I look forward to helping to continue to further develop the company.”
Dairy Crest will issue its half-yearly trading update on September 22 2014 and its interim results for the six months ending September 20 2014 on November 6 2014.