As with most racers, Aaron too started his career as a Kart racer. Still relatively young in the sport, he blazed his way through the National Karting Championships and went onto represent his country in 2004, at the Asian Karting Championships in Macau. His race at Macau was a blinder. Aaron broke the lap record, dominated right from the start and ended up with a win by a margin of over 3 seconds.
He was upgraded in 2005, to the Formula BMW Asian Series. His stint was threatened with a minimal budget as well as with four missed rounds in the championship but in what he got, Aaron clocked incredible times for a debutant and notched up five top-five finishes that included two third-place finishes.
In 2006, the youngster continued his motorsport education and participated in the Championship Class of the Formula BMW Asian series. He came in an overall position of fifth that saw him come second amongst other top-five finishes. In 2007, Lim moved up to the Formula Renault V6 Asia series for a limited year in the series. In the few races that Aaron participated in, he was on the podium for each. In the current season, Aaron will represent A1 Team Malaysia as the Rookie driver in the segment. He will be continuing his learning curve and under Alex Yoong, will be looking to learn a lot.