Now that Silverman has reached a divorce settlement with her estranged husband, Andrew Silverman, she and the X Factor judge are "100 percent together," an insider tells E! News exclusively.
Our source adds that they "are definitely a couple. The relationship is loving and they're very happy together."
Cowell is expecting his first child with Silverman.
The soon-to-be dad broke his silence on the baby news at the London premiere of One Direction's movie This Is Us on Tuesday, telling the BBC, "Things are changing in my life right now, for the better."
He added, "I'm proud to be a dad. It's something I haven't thought of before, and then, now I know I feel good about it. And she [Silverman] is a very special girl."
Meanwhile, Silverman was photographed arriving in the south of France on Wednesday to join Cowell for a vacation. Meanwhile, her 7-year-old son with Andrew Silverman, Adam, is with his father in New York.
For more on Cowell and Silverman's relationship, tune in to E! News tonight at 7 and 11:30 p.m. on E!