The "Little Fockers" and "Sin City" star and her husband, film producer Cash Warren, are already the parents of a 2-year-old daughter named Honor Marie. The couple married in 2008 after about four years of dating.
"I thought I'd drop by to let you all in on some exciting news -- Honor is going to be a Big Sister!" People.com reported Alba said in her online postings. "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!"
Alba did not disclose the baby's gender or anticipated delivery date.
Notable deaths of 2014 [PHOTOS]
Meg Ryan, Kiernan Shipka to star in 'Fan Girl'