Kerssenberg gave birth to Amadeus Benedict Edley Luis Becker in London on Tuesday.
"With this baby, my wife, Sharlely, gave me the most wonderful gift," said Becker. "We are all overcome and rejoice in our life together with our son and a sibling for Noah, Elias and Anna."
Amadeus is the couple's first child together, though Boris has three other children with an ex-wife and an ex-girlfriend.
Boris and his current wife, whose real name is Sharlely, married St Moritz, Switzerland last June. They now live in Wimbledon, England.