The announcement was made Monday by Bob Greenblatt, chairman of NBC Entertainment.
"Kelli and Danny are two great actors who will join a proven cast headed by Mariska Hargitay as this exceptional series heads into a very promising 13th season," Greenblatt said in a statement.
The show's executive producer/creator, Dick Wolf, said he was pleased by the cast additions.
"I know this combination will give us the opportunity to explore the world of 'SVU' with new eyes," Wolf said.
Giddish's TV credits include "Chase," "All My Children," "Damages," "The Good Wife," "Life on Mars" and "Without a Trace."
Pino starred for seven seasons on "Cold Case."
Longtime "SVU" star Chris Meloni confirmed last month he would not be returning for the show's 13th season.