The 'Snatch' director and Ainsley, who already have son Rafael, two, and daughter Rivka, 18 months, together, welcomed a third baby into the world recently, reported E! online.
Ritchie, 45, who also has sons Rocco, 13, and David, eight, with ex-wife Madonna, previously said he is a laid back dad who tries not to give his kids too much 'life advice' and thinks too much emphasis is placed on academia.
Ritchie and Ainsley have been in a relationship since 2010 and became engaged in 2012 after the director popped the question to the 32-year-old beauty at the Madeo restaurant in Los Angeles.