Together with his brother, Michael Hartono, at the age of 22 Robert inherited one of the leading cigarette company today, Djarum. Djarum was previously a small Business called Djarum gramophon which was later purchased by his Father, Oei Wie Gwan, in 1951 and changed its name to Djarum. Robert and his brother inherited Djarum after his Father died. At that time, Djarum's factory burned down and suffered an unstable condition. But in the hands of the two Hartono brothers, Djarum could grow into giants.
In a January 2018 billionaires' personal information, Budi Hartono and his brother Michael Hartono were reported by Forbes magazine as the richest men in Indonesia in 2018 with a combined wealth of $US 25 billion. Budi Hartono was listed by Forbes as being worth $US 12.6 billion, while in 2012 was $US 6.5 billion.