The child is the first for Silverstone and musician Christopher Jarecki, who married in 2005, UsMagazine.com said.
"My husband and I welcomed our 7 lb 15 oz baby boy Bear Blu Jarecki into the world on May 5 at 7:50 a.m. We are all three in love," the "Clueless" and "Excess Baggage" star wrote online. "I'm so grateful to this community for all the love, support, good wishes and happy vibes you've sent me during my pregnancy ... it has been wonderful. Thank you all!"
Celebrity Families of 2014 [PHOTOS]