He finished runner-up in the Spanish Rally Championship in 1986, in a Group B Renault 5 Turbo, and won it with a Ford Sierra RS Cosworth in 1987 and 1988.

Ford were an increasingly minor player in the World Rally Championship, with the rear-wheel-drive Sierra uncompetitive against the four-wheel-drive cars, and struggled to retain ambitious and talented young drivers such as Sainz and his teammate in 1988, Didier Auriol.

His teammate, by then two-time world champion Juha Kankkunen, also gave the Celica GT-Four ST165 its debut win at the inaugural Rally Australia.

In 1991, Sainz narrowly failed to defend his title against a resurgent Lancia-mounted Kankkunen, his efforts capped by a dramatic roll of his Celica in Australia which left him in a neckbrace.

Sainz's victory ahead of Ari Vatanen and Kankkunen, combined with Auriol's retirement, confirmed the title in favour of the Spaniard.

A limited number of 440 Celica GT-Four ST185s, carrying his name on a plaque in the vehicle, and with decals on the outside, were sold in the United Kingdom in 1992 in an attempt to capitalise on Sainz's two championship successes with the works team.

Sainz then chose to drive for the then fledgling Subaru World Rally Team in 1994, where he replaced Ari Vatanen.

Toyota won the manufacturers' title, but the drivers' championship was only settled on the final round, with Didier Auriol winning ahead of Sainz.

At this latter event he was trailing his teammate Colin McRae until the team ordered the Scotsman to slow down and allow Sainz to win, which led to a dispute between the drivers.

McRae won his home event 36 seconds ahead of Sainz, despite losing time with mechanical difficulties that at one stage had put him two minutes behind.

Subaru secured their first manufacturers' title with a triple win as the team's second young Briton, Richard Burns, finished third.

In 1996, he won the inaugural Rally Indonesia and with five other podium finishes to his name, he took third place in the drivers' world championship, behind Mitsubishi's Tommi Mäkinen and Subaru's McRae.

In the 1997 season, he again won the Indonesian round, along with the Acropolis Rally, but again lost the title fight to Mäkinen and McRae.

[13] A subdued season followed for Sainz in 1999, although it did at least culminate in a departing manufacturers' title for Toyota, by now fostering alternative interests in Formula One.

In 2002, Sainz inherited the victory of the Rally Argentina, having provisionally finished third, due to the disqualifications of the two leading Peugeots of Marcus Grönholm and Burns.

This was his only win of the season, and in a close fight for second place in the drivers' championship, behind the dominant Grönholm, Sainz finished third, one point ahead of his teammate McRae.

[14] In the championship, Sainz finished fourth, after missing out the final rally in Australia, due an accident during pre-event recce.

[15] Despite formally retiring at the end of the 2004 season, with a possible view to moving into the World Touring Car Championship, he was invited back to the WRC fold on the request of Citroën, to replace the faltering Belgian driver François Duval.

Although Duval was soon to reclaim his seat, Sainz's two rallies back in the Citroën impressed many, with the now 43-year-old Spaniard posting fourth and third finishing positions respectively.

Following the resignation of Fernando Martin, he even ran, eventually in vain, for the vice-president position at his beloved football club Real Madrid, for which he once trained.

Volkswagen's motorsport director Kris Nissen told that he needed "10 seconds" to convince Sainz to remain part of the company's efforts in the new programme.

[37] In November 2011, Sainz had the honour to drive first kilometres with the new Volkswagen Polo R WRC near Trier, Germany, when the team began testing the new car.

[38] In late 2011, Nissen also revealed he would like to see Sainz taking part in some rally with the WRC Polo before he calls time on his career.

[41] In October Sainz re-joined his old co-driver Luis Moya to perform course car duties on the San Marino´s annual Rally Legend event with Volkswagen's new-for-2013 Polo R WRC.

[42] In December 2012 Sainz dismissed rumours he would drive a Polo WRC in some of the WRC-rallies in 2013, but stated he was available for testing, if needed.

[47] However, in January 2023, Sainz suffered multiple spinal fractures after crashing at the Dakar Rally and was replaced by Mattias Ekström for the season.

[50] At the final two rounds of the season, the team finished in second and suffered a DNF respectively, losing the championship to RXR by 11 points.