In its latest Cost of Children research, released annually, the bank said the figure rises to more than £110,000 for those bringing up a child to the age of 11 in London; an increase of more than £25,000.
In comparison, the North of England spends £100 less than London on children per month.
Dr Keith White, founder of the Christian Childcare Forum, told Premier: "Christians are trying pretty hard.
"They really are trying to give it their best shot, and part of what they're doing is trying not to take their children out of the world...so that they're children can be salt and light right across society.
"There is a sort of peer group pressure. Another really important thing is that with usually both partners in a relationship having to work then you're into childcare costs and all the rest.
"There are costs of time, costs of emotion, and costs of prayer and heartache...monetary cost is just one of those elements.
"It is still worth it...but one shouldn't go into it starry-eyed. Children aren't just for Christmas."
Childcare costs makes up almost half of the £83,600 average, Halifax calculated.