The Chargers and Rivers jointly announced the veteran quarterback's decision Monday, with general manager Tom Telesco saying that the timing of the announcement will "allow everyone to put themselves in the best position for success in 2020."
Rivers, 38, is the most prolific passer in Chargers history, but he signaled last month that his time with the franchise likely was over when he moved his family from San Diego to Florida.
The eight-time Pro Bowler passed for 4,615 yards and 23 touchdowns -- his fewest since 2007 -- with 20 interceptions this past season, and Los Angeles struggled to a disappointing 5-11 record and a last-place finish in the AFC West.
"After stepping back a bit from last season, we reconnected with Philip and his representatives to look at how 2019 played out, assess our future goals, evaluate the current state of the roster and see if there was a path forward that made sense for both parties," Telesco said. "As we talked through various scenarios, it became apparent that it would be best for Philip and the Chargers to turn the page on what has truly been a remarkable run.
"We agreed that making this decision well before free agency would allow everyone to put themselves in the best position for success in 2020."
Rivers is sixth in NFL history in career passing yards (59,271) and touchdown passes (397). He led the Chargers to the playoffs six times in his 14 years as their starter, including an appearance in the 2007 AFC Championship Game.
"I am very grateful to the Spanos family [Chargers ownership] and the Chargers organization for the last 16 years," Rivers said in a statement. "In anything you do, it's the people you do it with that make it special. There are so many relationships and memories with coaches, support staff and teammates that will last forever, and for that I am so thankful.
"I never took for granted the opportunity to lead this team out onto the field for 235 games. We had a lot of great moments, beginning in San Diego and then finishing in L.A. I wish my teammates and coaches nothing but the best moving forward."
Rivers, speaking to the Los Angeles Times later Monday, reiterated what he said during the final weeks of the season about his intention to play in 2020.
"I do feel I have some emotional fire and passion still left," he said. "I know I have the passion for the game that I think is going to last my lifetime. And I think I have the ability left to go play at a high level.
"Some people might disagree that I can still play. But I would say I definitely can do it. I cleaned up a few of those other things, and if I'm playing consistently, I can still do it physically."
Rivers' 224 consecutive starts are the second most by an NFL quarterback, trailing just Brett Favre's total of 297.
"I've said before that Philip can still compete at a top starter level, and in a perfect world, No. 17 is your quarterback forever," Telesco said. "Obviously, we live in an imperfect world where the only constant is change. I think Philip's tremendous perspective, both when it comes to football and when it comes to life, helped lend clarity to a very complex situation."
Rivers was drafted fourth overall by the New York Giants in 2004 and was traded to the Chargers in a draft-day deal for Eli Manning. Rivers went on to set 30 franchise records with the Chargers, and his 123 wins rank him ninth among quarterbacks in NFL history.
"Through 16 seasons, 224 consecutive starts and more 'dadgummits' and 'shoots' than any of us can count, not only has Philip Rivers been our quarterback, he's been the heart and soul of our organization," Chargers owner Dean Spanos said. "He wore a bolo tie and cowboy boots to games. He introduced us to 'Nunc Coepi.' He always went out of his way to interact with the fans, and he even made fans of nuns. Over the years, I think he broke just about every team record in the book and, simply put, it was just fun to watch him play football.
"There's only one Philip Rivers, and we've been fortunate to call him our QB1 for the better part of two decades. We cannot thank Philip enough for giving it his all on every single down and for the memories he created that will last a lifetime."
The Associated Press contributed to this report.