Ajith entered the tinsel world at the age of 21 debuting in a Telegu movie 'Prema Pustagam' (1992) produced by Poorna Chandra Rao. The film which was a success earned him the 'Best New Face award' and paved the way for his entry into Tamil films. But, though his first film in Tamil 'Amaravati' (1993) directed by Ramesh Kumar did well, Ajith got involved in a motor bike accident by the time of its release. His spinal cord was badly affected which made him bed-ridden for weeks. Hence his second Tamil film 'Pavithra'(1994) got delayed for 17 months. The Tamil film industry wrote him off, but then came the super hit movie 'Aasai' (1995), which proved a turning point in his film career. It was 'Aasai'(1995) and the National Award Winner 'Kathal Kottai' (1996) directed by Agathiyan that elevated his career graph to the top. 

The following years saw a string of flops, except for a few films such as 'Aval Varuvala' (1998), 'Amarkalam' (1998), until the mega block buster 'Vaali' in 1999 which put him back in the superstar league and fetched him the Filmfare Best actor award that year. Throughout the Nineties, he acted in many successful movies in guest appearances and one remarkable feature was that his films during the period has picked up at least one award every year. And almost all his films have been dubbed or remade into Telugu. 

It was in 'Amarkalam' that he was paired for the first time with Shalini, his future wife to be. They later got married and is blessed with a baby girl, Anoushka.

 In the year 2000, he was cast alongside Mammooty and Aishwarya Rai in 'Kandukondain Kandukondain'(2000) which was impressive and played a supporting role in Shahrukh Khan's 'Asoka' (2001). He received Filmfare Best actor award for Villain in 2002. In the movie 'Varalaru' (2006) he played triple roles which include a role inspired by a Bharathanatyam dancer with feminine qualities. Directed by K S Ravikumar, the movie produced by NIC Arts Chakravarthy went on to complete a 100-days in 25 screens. The role got him a Film fare award for Best Actor for the third time. In 2007, his performance in the remake movie 'Billa'(2007) marked a new high in his acting career. Ajith has set up his own distribution company AK International.

 Besides films, he has dabbled with photography, has a pilot license and is the third Indian to take part in International Formula 3 race competitions. In fact he has a passion for motor car racing. Ajith also takes an active part of social service field and has created a non-profit organisation named Mohini-Mani Foundation in memory of his parents. He is an ambassador for the Green Revolution, the organisation which makes an effort to clean up the Chennai environment and encourage people to plant saplings. 

Ajith was the only self-made hero in the Nineties who survived and prospered without any filmy background whatsoever. Personally, Ajith the star who has a huge fan following worldwide is very down to earth in nature and is much appreciated for his kindness and confidence.