Spanos announced the decision after speaking with Smith on Monday night and Turner on Tuesday morning. The Chargers finished 8-8 to miss the playoffs for the second consecutive season, but Spanos said he hasn't thought about the ramifications of not making the postseason again next time.
"Bottom line, I believe these two men give us the best chance to get back to the playoffs," Spanos said in a statement. "A.J. Smith is the best man to improve our roster, and Norv Turner is the best man to lead that roster on the field."
Both Smith and Turner have signed long-term contract extensions in recent years. Smith received a five-year contract extension in 2008 to keep him with the team through 2014. Turner was locked up with a three-year contract extension through 2013. Spanos said those financial commitments didn't factor in his decision.
"You have to evaluate everything, every year," Spanos told reporters. "If it warrants changes, it warrants changes. Iâve never had a second thought about making changes."
Turner is 49-31 in five seasons and 3-3 in the playoffs. The Chargers went 4-1 at the beginning and end of this season, but they were undone by a six-game losing streak in the middle of the season that Spanos described as "pretty damn depressing." One more win would have earned the Chargers the AFC West title.
"I was excited," Turner said about hearing the news that he would return. "I've been excited about this team for a long time. I think probably the most important thing to me, that meant the most to me, is the number of key players who responded the way they did (over the final few games)."
Smith has come under fire for the erosion of talent from a roster that at one time was considered among the NFL's best. His most recent drafts have produced more busts than impact players, and the Chargers have just three of their last seven first-round draft picks on the active roster.
"Clearly, the last two years, the arrow has been pointing down," Spanos said. "There's no doubt about it. But I think that can change very quickly."
The Associated Press contributed to this report.