The 27-year-old took to Instagram to announce the news and shared a sonogram photograph of their baby, reports eonline.com.
"This is where my heart is," Palmer posted, adding: "To my precious baby - I'm so blessed to be your mama, we have been wishing for you for awhile. We love you so much and can't wait to kiss your little face and tiny toes. Thank you for hearing our prayers. @likemark."
In the Instagram picture, Palmer shows off the sonogram with two-knitted baby boots. Teresa Palmer and Mark Webber announced their engagement earlier this month.