The 39-year-old "CSI: Cyber" star shared the news on Instagram.
"Happy to share that two days ago, Kimberly and I were lucky enough to welcome a little baby girl into the world. Emilia Van Der Beek," he captioned the picture of his wife along with their four kids.
Back in January 2014, Kimberly gave birth to the couple's third child, a baby girl named Annabel Leah, who joined older brother Joshua, and sister Olivia.
James and Kimberly, 34, announced their happy news in November.