The 29-year-old former Hearts defender has been training with Leeds, who have now handed him an initial deal until the end of the season.
"I'm delighted to sign Marius," said Leeds manager Brian McDermott.
"He is a player with a lot of experience, he has played for his country, and he's a good age for a centre-half. It's fantastic to have him on board."
Zaliukas has been a free agent since leaving Hearts in the summer, and he turned down offers from Rangers and Queens Park Rangers.