The couple welcomed their first child together last September, but have only now revealed his name, reported Femalefirst.
"We thought Raffie Ritchie sounded really cute when shortened. His older brother, Rocco, helped choose the name - we were throwing ideas out there as a family and it stuck from early on," Ainsley said.
Guy, 43, has two sons Rocco, 11, and an adopted son David, six, from his marriage to Queen of Pop Madonna, 53, who he divorced in 2008.
Rafael is Ainsley's first child.
"He has two great brothers which is really lovely. I'm the happiest girl in the world and loving motherhood," Ainsley added.