The team scheduled a Friday morning news conference at Yankee Stadium for Pettitte to announce the choice he had been leaning toward making since the end of last season.
"I don't think enough people know that he's still the leader of this pitching staff until today," former Yankees right fielder Paul O'Neill said in a telephone interview with The Associated Press.
A five-time World Series champion, Pettitte became the third-winningest pitcher in team history.
"Andy was probably the consummate team player," former Yankees manager Joe Torre said. "He's been a huge favorite of mine because he's such a standup guy, and he hasn't changed from day one. He's a great teammate, and I think that's why he won so many games. The guys that play behind him understand how intense he is, and it becomes contagious."
• VERDUCCI: Pettitte never stopped loving pitching
Pettitte won't disappear from public view entirely. He is expected to be a witness this summer at the trial of former teammate Roger Clemens, indicted on charges he lied to a congressional committee when he denied using performance-enhancing drugs.
Pettitte admitted using human growth hormone and said Clemens told him he had used HGH. Clemens testified Pettitte didn't remember the conversation correctly.
Clemens said Thursday he hasn't been able to speak with Pettitte lately because of the ongoing case. But he insisted he held no hard feelings toward Pettitte and congratulated him on his career.
"If I know the age of his oldest one, I think he's a freshman or sophomore in high school, so it's a crucial time to be around. I'm sure that weighed on him for a number of years," said Clemens, speaking to reporters before a baseball banquet in Corpus Christi, Texas.
Pettitte's retirement creates a great uncertainty for the Yankees. New York has no proven starters behind CC Sabathia, Phil Hughes and A.J. Burnett, who struggled during the second half of last season.
Having failed to sign free agent Cliff Lee, New York has agreed to minor league contracts with Bartolo Colon and Freddy Garcia in recent weeks, trying to find more options for a fourth and fifth starter in addition to youngster Ivan Nova and Sergio Mitre. The Yankees also are interested in signing Kevin Millwood, a person familiar those conversations said Thursday. The person spoke on condition of anonymity because talks are ongoing.
Pettitte finished 240-138 with a 3.88 ERA in 16 major league seasons. He excelled in the postseason, setting a major league record for wins by going 19-10 with a 3.83 ERA.
• CORCORAN: Pettitte's retirement leaves Yankees scrambling
"You're going to miss him taking the mound every fifth day. You're going to miss having him as your No. 1 or No. 2 starter going into the playoffs," said O'Neill, a former teammate and current broadcaster for the Yankees' YES Network. "But you're really going to miss just how he helps younger players and how he helps pitching staffs as a veteran pitcher who's really been though pretty much everything as a New York Yankee."
A member of the "Core Four" along with Derek Jeter, Mariano Rivera and Jorge Posada, Pettitte helped the Yankees win World Series titles in 1996, 1998, 1999, 2000 and 2009.
"The Yankees have been fortunate to have him representing the organization both on and off the field," said Jeter, the team captain, "More importantly it's been an honor to get to know him as a person, and I consider him family."
Pettitte first came up to the Yankees in 1995, the year before the start of the team's latest era of dominance.
"I liked the guy from the first moment I met him," Whitey Ford said. "After watching him a few times, I really thought he could be a great pitcher.
Pettitte spent 13 seasons with the Yankees, interrupting his career in New York to play for his hometown Houston Astros from 2004-06. He was a three-time All-Star, earning the honor in 1996, 2001 and last year, and was a 20-game winner in 1996 and 2003 when he twice went 21-8.
"He was a fighter and all about winning, and he was respected by every person in the clubhouse," Rivera said.
In both 1998 and 2009, Pettitte won the World Series finale.
"Without him we don't win all four World Series," former Yankees first baseman Tino Martinez said. "Since I've been retired, I'm always asked, 'Who would you have pitch a World Series Game 7?' And I always say, 'Andy Pettitte.'"
Pettitte was 11-3 with a 3.28 ERA in 21 starts last season. His season was limited by a strained left groin that caused him to go on the disabled list from July 19 to Sept. 19.
"I'm really sad that Andy is going to retire," Posada said. "He was so much more than a teammate to me -- he was one of my closest friends."
Pettitte had said he increasingly felt the tug to return to Deer Park, Texas, and his wife and four children. Once the school year ended, his family traveled to New York where they could be together during homestands, but the distance from his loved ones now has trumped whatever desire he had to climb higher in the Yankees record book.
"Now it seems like he's at the point of his life where he's not willing to make that commitment," O'Neill said. "He's had a wonderful career. Fans have to respect what he's going to go do now, which is to live his life and let his kids live their lives."
Pettitte leaves with 203 wins for the Yankees, trailing only Ford (236) and Red Ruffing (231). He is second to Ford in strikeouts (1,823) and starts (396).
"One of the tops the Yankees ever had," Yogi Berra said. "He's always a guy you always depend on, and we're gonna miss him."