The right-hander, 29, is a non-roster invitee who has Major League experience with Houston and the Mets, most recently in 2010. He spent most of last year pitching in Korea for the Doosan Bears, and was limited to five Minor League starts in 2007 because of Tommy John surgery.
Jamey Wright came into camp as the favorite for the long relief role because of his experience, but the Dodgers have 11 non-roster pitchers in camp, nine with Major League experience.
"Nieve is a little more of a power guy out of the 'pen. He reminds me of Ramon Ortiz," said manager Don Mattingly. "His stuff is good and he's durable. That's what we need in that role."
Nieve has allowed one run in 5 1/3 innings, with three strikeouts and no walks.