Reg Bailey, who is from a business background, was the unanimous choice of the 22 women on the ruling council. He is the first man to hold the position in the organisation's 120-year history.
The Mothers' Union, set up to promote monogamy and Christian values, has tried to shake off its traditionalist image in recent years. It has set up branches in prisons, called for the legalisation of brothels and questioned the importance of the nuclear family.
Just 150 of its one million members world-wide are men. Mr Bailey, 49, who is married with two children, is not among them, although his wife is secretary of her local branch.
His appointment was defended yesterday by Christine Eames, the world- wide president. She said that Mr Bailey had the right qualities for the job, including "considerable experience in management" and "a very successful business career".
"As an organisation that is committed to equality for everyone, we felt we should look at the applicants as people, rather than as men or women," said Lady Eames. "We also recognise that family life is not just a women's issue.
"We were fortunate in attracting candidates of a very high calibre, and we felt Reg was the person with the experience and the gifts to take the organisation forward into the new millennium."