Grayston Burgess, who is also an accomplished conductor, warned the voice of Carris Jones would not be in keeping with other sounds produced by the traditionally all-male choir.
The 84 year old told the Telegraph: "It's a politically correct appointment that has nothing to do with musical know-how. It's nonsense to introduce a woman into a traditional boys choir.
Last month, it was announced that Carris had been unanimously selected to join the ranks of the St Paul's Cathedral Choir, making her this first women to do so in the choir's 1,000 year history.
At the time, she said: "I am thrilled to be appointed as a Vicar Choral at St Paul's Cathedral, and feel incredibly lucky to join a group of such friendly and talented musicians.
"I have long admired the cathedral as an organisation that manages to combine a venerable historical tradition with a vital place in 21st century London life, and am honoured to become a part of it."
Mr Burgess, who established the choral scheme Choir 2000, said: "Boys make a totally different sound to an adult when they sing and, with her appointment, St Paul's will no longer be a boys choir.
"Why are they trying to change something that's been here for thousands of years?"
The Cathedral Choir currently comprises of 26 boy treble Choristers, eight probationers and twelve Vicars Choral - the professional adult singers who take the alto, tenor and bass parts.
St Paul's Director of Music, Andrew Carwood, said last month: "We are delighted that Carris is joining the Choir. The final round of auditions was of a very high standard and her appointment was a unanimous decision."