Had Kartika's punishment been carried out at the time of her sentencing in July, she would have been the first woman to be caned in Malaysia, where about 60 per cent of the 28 million people are Muslims.
Kartika was sentenced to six strokes of the cane and a fine of 5,000 ringgit ($1,400) for drinking beer in December 2007 at a beach resort.
Malaysia follows a dual-track justice system. Shariah laws apply to Muslims in all personal matters; non-Muslims are covered by civil laws, and are free to drink.
Only three states in Malaysia - Pahang, Perlis and Kelantan - impose caning for drinking alcohol. In the other 10 states it is punishable by a fine.
Kartika pleaded guilty and did not appeal her sentence, but the punishment was
halted at the last minute following an uproar in the media and among rights activists.
Adham Jamalullail, Kartika's lawyer, told the Associated Press news agency that "as a substitution for the caning, the sultan has ordered Kartika to perform community service for three weeks".
Sultan Ahmad Shah is the guardian of Islam in Pahang and its titular head. Most of Malaysia's 13 states are ruled by sultans who usually play a ceremonial role in governance but have the power to rule in Islamic matters.
Shukarno Abdul Muttalib, Kartika's father, said she has been told to report to the Islamic department early on Friday.
"We will abide by the order ... Kartika will go on with her life,'' he said.
The sultan's decision followed Kartika's meeting with the Pahang crown prince last month.
Officials had said the caning would be very different to the corporal punishment administered on male criminals under secular civil laws.
Drug offenders, kidnappers and others are caned with a thick rattan stick on bare
buttocks that break the skin and leave lifelong scars.
Kartika's punishment under Islamic laws would have been delivered with a thin cane on the back with her clothes on.
However, in the meantime three other Muslim women were caned for having sex out of wedlock, becoming the first Muslim women to be caned in Malaysia.
Their cases did not draw as much attention because the caning was kept a secret until after it was done.
Subsequently, the women themselves appeared before local media and said they deserved the punishment.