Froome signed for Team Sky at the start of the 2010 season and finished second at the Vuelta a Espana a year later. He finished second at the Tour de France in 2012 - behind his then teammate Bradley Wiggins - but returned to win the race a the following year. He crashed out during the defence of his title in 2014 but beat Nairo Quintana into second place last July to secure his second Tour de France title.
"Team Sky have been fundamental to my success to date, so it was a very easy decision to commit to the Team until the end of 2018. Their values are my values and I am proud to ride for a team that has shown that you can win the biggest bike races in the world clean. 2015 was a fantastic year for me both professional and personally and this is a great kick start to 2016. I am more motivated than I have ever been and I have got big targets for this Olympic year. I can't wait to start racing."
The 30-year-old will once again target the Tour de France in 2016, along with the Olympic Games.
On announcing the news, Team Sky's Dave Brailsford said: "By 2020, when we look back on the decade, we want Team Sky to be seen as the most consistent and successful Grand Tour team as well as one that is regularly winning Classics. 2015 was a good year and I am proud of what we achieved together but our appetite for success has never been greater.
"Chris is not only one of the most talented and dedicated riders in the world, he is also a fantastic ambassador for the sport. Team Sky is proud to have him as our team leader. He is a winner and it is a great boost at the start of the new season that he has committed to stay with the Team to the end of 2018. He is hungry for more success and we will help him achieve it."
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