Kiffin replaces Rob Ryan, who was fired on Tuesday.
Earlier in the week, the Cowboys fired running backs coach Skip Peete.
Cowboys owner Jerry Jones vowed change after the Cowboys finished 8-8 and out of the playoffs.
Kiffin, who was at Valley Ranch all day on Thursday and today, is expected to move the Cowboys from the 3-4 alignment to a 4-3 scheme.
The 72-year-old Kiffin, a 47-year coaching veteran, is widely praised for his "Tampa 2" defense, which puts two safeties deep and relies on speed, tackling and a versatile middle linebacker who can drop into coverage.
Kiffin coached 26 years in the NFL, including 13 as Tampa Bay defensive coordinator before moving to the college ranks to handle the defense for his son Lane’s teams at Tennessee in 2009 and at Southern Cal the past three seasons.
Kiffin resigned after the 2012 season in which the Trojans’ defensive failures were heavily criticized, and was said to be seeking a return to the NFL.
Well, he’s back.
The move to Dallas caught former Bucs linebacker Derrick Brooks by surprise.
"I would never have guessed Dallas two weeks ago," said Brooks, who still keeps in touch with Kiffin.
"I don’t know if he has the players there yet. I hope he does," Brooks added. "I just know what we did to make our defense great. Some would say it’s so simple, but at the same time, it’s so complex. You always hear about Dallas, ’They’ve got talent. They’ve got talent.’ Well, now it’s time to roost. They can answer the question: Do they really have talent?"
The Cowboys believe inside linebackers Sean Lee and Bruce Carter can make the conversion to middle linebacker and weakside linebacker, respectively. That would necessitate finding a strongside linebacker.
Outside linebacker DeMarcus Ware would move to defensive end. Rushing the passer every down would likely put more wear and tear on him, and it would signal the end of his dropping into coverage.
If the Cowboys don’t re-sign Anthony Spencer to play defensive end opposite Ware, that position becomes a focal point in the April draft.
Defensive end Jason Hatcher and nose tackle Jay Ratliff would man the two tackle positions in the 4-3.
Brooks knows one thing: Kiffin will be more motivated than ever after four years in the college game coaching for his son and a disappointing departure from the Bucs in 2008.
"Our defense once he made that announcement he was leaving, it’s on record we didn’t play well," Brooks said. "That doesn’t sit right with him. I know that bothers him. He is motivated in that sense. He wants to earn his reputation back."
-- Clarence Hill, Charean Williams