The couple are now proud parents to a little boy named Liam, born on Tuesday weighing 10lbs.
"Beautiful Bojana gave birth to 10lb Liam today, the most important day of the week," NCIS star Michael announced in a light-hearted post, sharing both his happy news, and a playful plug for the show with nearly 300,000 followers.
Michael, 45, and internist Bojana, 32, announced their pregnancy in April. Speaking at the time, they told US Weekly that they were still undecided on names; Bojana is of Serbian descent, while Michael has an Irish background.
"There are many names being discussed. Some are very controversial. We have some Serbian names and some Irish names," Michael confirmed.
The couple married in 2009 after dating long-distance for two years. In April, 2012, they welcomed their first child together, daughter Olivia.
Dark Angel actor Michael is also a father to 17-year-old son August, from his first marriage to Amelia Heinle.
He was previously engaged to his Dark Angel co-star Jessica Alba, but the couple ended their engagement after two years, in 2003.
Michael stars as senior field agent Tony DiNozzo on NCIS, and has been with the hit drama series since it began in 2003.