Huxley uses irony throughout the novel, primarily in a satirical way. For instance, characters in BNW frequently refer to Henry Ford in the same manner that we would refer to Jesus or God. Instead of AD (anno domini, or "The year of our Lord,") characters refer to "the era of our Ford." Expressions like this are ironic because you and I are not inclined to think of an auto manufacturer on this level, but members of this society don't give it a second thought.
The purpose of Huxley's irony is mainly to demonstrate in a humorous way how thoroughly different this society is from our own. This "brave new world" has been completely manufactured to suit the purposes of the few members of the ruling class, who desire people to revere technology instead of any type of religion.