The Peugeot driver completed the 14-day offroad event in 49 hours 16 minutes and 18 seconds, almost 44 minutes ahead of Toyota's Nasser Al-Attiyah of Qatar, reports Xinhua news agency.
South Africa's Giniel de Villiers, who won Saturday's final 120km timed section, came third, more than an hour and 16 minutes off the pace.
Sainz, a two-time world rally champion, won the Dakar in 2010 with Volkswagen but failed to complete the previous three editions of the race.
"(Peugeot) have already won two times, but I think I deserved this victory because we have put a lot of effort into this car," said the 55-year-old father of Renault Formula One driver Carlos Sainz Jr.
"I had ups and downs but I always tried my best. Especially this rally, it has been so, so hard.
"At the beginning I said we'll take it a little bit easier, but Peugeot said we'd have to go flat out. I raced a couple of days and pushed really hard, but then the race was a case of not making mistakes."
Carlos Jr sent his congratulations via social media.
"I am probably the proudest son of his father in the whole world. Winner of the toughest Dakar ever done in South America at 55 years of age (good number) and he did it in his own way," said Sainz Jr, whose Formula One number is 55.
Austria's Matthias Walkner secured the 17th consecutive Dakar motorcycle title for KTM, beating Honda's Argentine rider Kevin Benavides by almost 17 minutes. Australian Toby price was third on a KTM.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
