"We are so excited and feel so unbelievably lucky to have this little person coming to us!" the couple tells the magazine in a statement. Enos, 38, and Ruck, 57, already have a 3-year-old daughter, Vesper Vivienne. The two married in 2008.
Ruck is also dad to Emma, 26, and Sam, 19, from a previous marriage.
Enos will reprise her role as Det. Sarah Linden for the fourth and final season of The Killing, which premieres later this year on Netflix. Also known for his series role on Spin City, Ruck most recently guest-starred on Psych.