Karthikeyan was born in Madras, Tamil Nadu. Karthikeyan did his schooling at Stanes Anglo Indian Higher Secondary School in Coimbatore. He belongs to PSG Family in Coimbatore.His father Mr.G.R Karthikeyan has been "Managing Trustee" of PSG and Sons Charities which runs PSG industrial Institute, PSG Polytechnic College,PSG College of Arts and Science, PSG College of Technology, PSG Institute of Medical science and Research, PSG Hospitals, PSG INstitute of Management etc.Narain Karthikeyan also runs Karthikeya Spinning Mills LTD and a wind energy sector and many other companies in Coimbatore. Karthikeyan's interest in motorsport began at an early age, as his father was a former Indian national rally champion winning South India Rally seven times. He is also related to the late S. Karivardhan, India's most famous racing driver until Karthikeyan came along. With the ambition of becoming India's first Formula One driver, Karthikeyan finished on the podium in his first ever race, at Sriperumpudur in a Formula Maruti (a.k.a.FISSME). He then went onto the Elf Winfield Racing School in France, showing his talent by becoming a semi-finalist in the Pilote Elf Competition for Formula Renault cars in 1992. He returned to India to race in Formula Maruti for the 1993 season, and in the same year, he also competed in the Formula Vauxhall Junior championship in Great Britain. This gave him valuable experience in European racing, and he was keen to return for the following year.
In 1994, he returned to the UK, racing in the Formula Ford Zetec series as the number two works Vector driver for the Foundation Racing team. The highlight of the season was a podium finish in a support race for the Portuguese Grand Prix held at Estoril. Karthikeyan also took part in the British Formula Ford Winter Series, and became the first Indian to win any championship in Europe.
In 1995, Karthikeyan graduated to the Formula Asia Championship for just four races. However, he showed pace immediately and was able to finish second in the race at Shah Alam, Malaysia. In 1996, he had a full season in the series and became the first Indian and the first Asian to win the Formula Asia International series. He moved back to Britain in 1997 to compete in the British Formula Opel Championship with the Nemesis Motorsport team, taking a pole position and win at Donington Park and finishing sixth in the overall points standings.
In 1998, Karthikeyan made his debut in the British Formula Three Championship with the Carlin Motorsport team. Competing in only 10 rounds, he managed two third place finishes in the final two races of the season, at Spa-Francorchamps and Silverstone, to finish 12th overall. He continued in the championship for 1999, finishing on the podium five times, including two wins at Brands Hatch. His season also included two pole positions, three fastest laps and two lap records, helping him to sixth in the championship. He also competed in the Macau Grand Prix, qualifying in sixth position and finishing sixth in the second race. Continuing his drive in the British F3 Championship in 2000, he finished fourth overall in the standings, and also took pole position and fastest laps in the Macau Grand Prix. He also won both the International F3 race at Spa-Francorchamps and the Korea Super Prix.
Karthikeyan started 2001 in the Formula Nippon F3000 Championship, finishing the year amongst the top ten. In the same year, he became the first Indian to ever drive a Formula One car, testing for the Jaguar Racing team at Silverstone on 14 June. Impressed with his performance, he was then offered a test drive in the Jordan-Honda EJ11 at Silverstone in September. Karthikeyan again tested for Jordan, at Mugello in Italy on 5 October, finishing just half a second off the pace off Jordan's lead driver Jean Alesi.
In 2002, he moved into the Telefonica World Series with Team Tata RC Motorsport, taking a pole position and setting the fastest non-Formula One lap time at the Interlagos Circuit in Brazil. Continuing in the renamed Superfund Word Series in 2003, Karthikeyan won two races and took three other podium positions on his way to fourth overall in the championship. These results earned him another Formula One test drive, this time with the Minardi team. He was offered a race drive for the 2004 season, but was unable to raise the necessary sponsorship funds to seal the deal. During the year, he married Pavarna.