Berlin - Nico Rosberg quit Formula One on Friday, just five days after winning the world title for Mercedes in a move that stunned motor racing.
The 31-year-old German, who beat off team-mate Lewis Hamilton in the finale, is the first reigning champion to quit since Alain Prost in 1993.
Rosberg made the bombshell revelation in Vienna ahead of the International Automobile Federation (FIA) annual awards ceremony.
"I have decided to end my Formula One career here," said Rosberg, who claimed the title at the Abu Dhabi Grand Prix on Sunday when he came second to Hamilton.
He said he made the decision in the aftermath of his championship triumph.
"It was a process on Monday," Rosberg added. "I didn't know if I had the balls, and I took a bit of time.
"But I am done. End of story, and the next step is being a dad and a husband and I am very much looking forward to that."
Mercedes team boss Toto Wolff said: "For the team this is an unexpected situation and an exciting one."
Wolff hailed the achievements of Rosberg.
"This is a brave decision by Nico and testament to the strength of his character.
"He has chosen to leave at the pinnacle of his career, as world champion, having achieved his childhood dream."
Wolff said Rosberg's "relentless" drive and "inspirational way" of fighting adversity, mixed with his "tenacity and grace under pressure" had earned him "the respect of the sport".
In capturing the title Rosberg emulated his father Keke who won the F1 crown in 1982.
Rosberg began karting aged six. He and Hamilton met as rivals in 1997 and became team-mates in 2000.
In 2002, he moved to the German Formula BMW championship and won the title.
Rosberg arrived in F1, with Williams, via the Formula 3 Euro Series and winning the inaugural GP2 title in 2005.
Before joining Williams, he turned down a place at Imperial College, London, to study aeronautical engineering.
Rosberg claimed his first podium at the 2008 Australian Grand Prix, sharing the moment with a victorious Hamilton who had arrived in F1 with McLaren a year earlier.
In 2010, he moved to the rebranded Mercedes team created by the German manufacturer’s takeover of the 2009 champions Brawn.
He recorded consistent finishes as team-mate to returning Michael Schumacher before the seven-time champion’s final retirement and the arrival, in 2013, of Hamilton.
Their partnership ignited the team’s spell of dominance. Though Hamilton beat him to be champion in 2014 and 2015, the methodical Rosberg finally took the crown in 2016.
Rosberg takes his leave of Formula One with 23 race wins and 30 pole positions.
He is now relinquishing life in the fast lane to spend time with his wife, his childhood sweetheart Vivian Sibold with whom he has a daughter, Alaia, born in August last year.
He posted a message to his fans on social media, saying "I have a message for you".
"Since 25 years in racing it has been my dream, my 'one thing' to become Formula One World Champion. Through the hard work, the pain, the sacrifices, this has been my target.
"And now I've made it. I have climbed the mountain, I am on the peak, so this feels right."
Wolff said Rosberg's exit presented Mercedes with "an unexpected but exciting situation".
"We are going into a new era of technical regulations and there is a free Mercedes cockpit for the seasons ahead."
Following is the full statement he issued to his fans via a Facebook page:
"Since 25 years in racing, it has been my dream, my 'one thing' to become Formula One world champion. Through the hard work, the pain, the sacrifices, this has been my target. And now I've made it. I have climbed my mountain, I am on the peak, so this feels right. My strongest emotion right now is deep gratitude to everybody who supported me to make that dream happen.
"This season, I tell you, it was so damn tough. I pushed like crazy in every area after the disappointments of the last two years; they fuelled my motivation to levels I had never experienced before. And of course that had an impact on the ones I love, too – it was a whole family effort of sacrifice, putting everything behind our target.
"I cannot find enough words to thank my wife Vivian; she has been incredible. She understood that this year was the big one, our opportunity to do it, and created the space for me to get full recovery between every race, looking after our daughter each night, taking over when things got tough and putting our championship first.
"When I won the race in Suzuka, from the moment when the destiny of the title was in my own hands, the big pressure started and I began to think about ending my racing career if I became world champion.
"On Sunday morning in Abu Dhabi, I knew that it could be my last race and that feeling cleared my head before the start. I wanted to enjoy every part of the experience, knowing it might be the last time...and then the lights went out and I had the most intense 55 laps of my life.
"I took my decision on Monday evening. After reflecting for a day, the first people I told were Vivian and Georg (Nolte, from Nico's management team), followed by (Mercedes team boss) Toto (Wolff).
"The only thing that makes this decision in any way difficult for me is because I am putting my racing family into a tough situation. But Toto understood. He knew straight away that I was completely convinced and that reassured me. My proudest achievement in racing will always be to have won the world championship with this incredible team of people, the Silver Arrows.
"Now, I'm just here to enjoy the moment. There is time to savour the next weeks, to reflect on the season and to enjoy every experience that comes my way. After that, I will turn the next corner in my life and see what it has in store for me"
Nico Rosberg factfile after the German's shock retirement from Formula One on Friday:
Born: 27/06/1985 (age 31)
Place of Birth: Wiesbaden, Germany
Teams: Mercedes (2010-2016), Williams (2006-2009)
Driver number: 6
Grands Prix entered: 206
World Championships: 1 (2016)
Race wins: 23
Pole positions: 30
First race: 2006 Bahrain Grand Prix
First win: 2012 Chinese Grand Prix
Last race: 2016 Abu Dhabi Grand Prix
Last win: 2016 Japanese Grand Prix