The actress announced on her Facebook page and Twitter account Wednesday that she and her husband are expecting their second child.
"I thought I'd drop by to let you all in on some exciting news – Honor is going to be a Big Sister!" Alba, 29, wrote.
"Cash and I are thrilled and wanted to share the news directly with you so you didn't hear about it somewhere else.
"I appreciated all of the love and support you all gave me during my first pregnancy and will definitely appreciate it again this time around. Have a great day!" she finishes, signing off, "Jess."
Warren also posted to his Twitter page, "@jessicaalba are beyond excited about the news! Honor is going to be a great big sister. Thank you all for the wonderful messages!!"
Alba delivered daughter Honor Marie, 2½, in June 2008, a month after marrying Warren in California.