The redesign was the idea of chief executive Michael O'Leary and it was spotted by workers at Stansted airport.
The new logo is to appear on the 150 new Boeing 737-800 jets, which are flown by 24m each year.
According to a spokesperson for Ryanair: "We haven't boobed and we are not trying to milk a situation either.
"It was handled for aerodynamic purposes, as we move to an all-new Boeing 737-800 fleet, it was to give our 24m passengers a more uplifting experience," he said.
The new look was quietly introduced without much fanfare, but was spotted by workers at Standsted Airport who were quick to notice the new look.
The spokesperson said: "Bosses thought the angel was flat-chested and someone ordered, 'Give her bigger boobs. We want her to stand out'. We all think it's great. She certainly gets noticed a lot more now. We know Mr O’Leary has a sense of humour and this proves it."
The news came as Ryanair was ordered by the Advertising Standards Authority to stop claiming that its flights to St Etienne go to Lyon, after complaints from a passenger that it was misleading. St Etienne and Lyon are 46 miles apart.
The airline is also facing a court case over charging a disabled passenger £18 for use of a wheelchair when boarding one of its flights.
If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the Forum here.