"This is where I was raised and it's an amazing opportunity for me to stay in the city I grew up in," said Quentin, who grew up south of downtown in Chula Vista and attended University of San Diego High. "I believe in this organization. My family is very excited."
The extension -- first reported by CBSSports.com -- has Quentin making $9.5 million in 2013, $9.5 million in 2014 and $8 million in 2015. There's a mutual option for 2016 worth $10 million, though Quentin can assure himself of $3 million in 2016 if he plays in 320 games over the next three seasons.
The deal also includes a no-trade clause.
Quentin, who missed the first 49 games of the season after having knee surgery in Spring Training, has a .273 average with nine home runs and 22 RBIs and a .389 on-base percentage in 40 games since he was reinstated from the disabled list on May 28.
"He's a proven middle-of-the-order bat, which we need, he brings an intensity, an edge, a swagger to our team which we need," Byrnes said on Sunday. "It's a risk, but we feel it's a risk we have to take."
Quentin hit five home runs in his first six games after coming off the disabled list, but cooled thereafter. Since July 7, he's hitting .294 with two home runs and six RBIs in his last 34 at-bats for a team that has scored seven or more runs on seven different occasions this month.
In the first 49 games of the season, the Padres were 17-32 and averaged 3.1 runs per game with a .220 team average. After Quentin returned, the team is 23-24 and is averaging 4.3 runs per game.
Quentin, 29, is owed $7.025 million this season, his first with the team after he was obtained from the White Sox on Dec. 31 for two Minor League pitchers.
"Acquiring Carlos this winter and having Carlos for the next number of years adds great continuity to a club that is starting to see some players emerge," said Padres manager Bud Black. "He's a guy who I think you can put in the middle of our order and feel good about on a daily basis.
"I think it sends a great message to the community and to the players. The players are excited about this ... there's a lot of positives to this one."
Quentin thanked Byrnes and his agent, Brodie Van Wagenen for getting the deal done relatively quickly and without offering much in the way of a distraction from playing. Byrnes and Van Wagenen met late last month in Houston and Van Wagenen was in San Diego this week as the two sides hammered out a deal.
"We didn't want to have an extended negotiation, we had a period where we could sit down, roll up our sleeves and see if we could get a deal done. All of the factors lined up this week," Byrnes said.
Quentin's presence has allowed teammates such as Chase Headley and Yonder Alonso to slide into spots in the batting order where they're more comfortable and where they've seen a better set of pitches.
"I think he's a much-needed power threat in the middle of the lineup that every team needs. He kind of lets everyone slide into their position so that it extends our lineup and everyone gets to fit a little better than where they normally would," Headley said.
"He's been a big part of our offensive turnaround."
Byrnes said he sought and received approval from majority owner John Moores and the "prospective ownership" that is believed to be the O'Malley group.
The extension with Quentin didn't rate as a big surprise.
Earlier this month, Byrnes, when he was asked about the July 31 trade deadline, said "we don't have to trade anyone."
There's a thought internally that the team might opt to offer a contract extension to All-Star closer Huston Street as well. Street is 2-0 with a 0.99 ERA and is 15-for-15 in save opportunities.
"This is not a roster we want to tear down," Byrnes said in response to the multitude of reports that the Padres will be selling off players before the July 31 trade deadline.
"It's a roster we want to build."