His appointment has raised questions about Abhisit's commitment to reaching out to supporters of Thaksin Shinawatra, the former prime minister ousted in a 2006 coup and now convicted of corruption and living in exile but still popular among the rural masses.
Abhisit pledged in his inaugural address to restore Thailand's tourist-friendly image, damaged by six months of political turmoil that culminated in an eight-day siege of Bangkok's airports late last month that stranded more than 300,000 travellers.
The 44-year-old's elevation to the prime minister's post came after a court dissolved the People Power party leading the previous government, which was packed with Thaksin's allies.
Korn, also 44, is a respected economist and former investment banker who headed Thailand's office of JP Morgan Chase & Co from 1999-2004.
But Kasit, 64, is a controversial choice.
The former ambassador to Japan, Germany, Indonesia and the former Soviet Union appeared several times as a guest speaker at the months-long protests led by the PAD.
He even praised the November 29-December 3 airport blockade as a "new innovation for public protests".
Another Abhisit pick has been linked to corruption.
The Democrat party's secretary-general Suthep Thaugsuban, 59, was appointed deputy prime minister to oversee security matters.
Suthep was accused in 1995 of distributing plots of land allotted for agricultural use by the poor to his cronies. The scandal brought down the administration of the then prime minister, Chuan Leekpai, a Democrat.
Chavarat Charnvirakul, 72, a former Thaksin supporter who defected to the Democrats, was rewarded with the interior minister's portfolio.
Chavarat was a deputy prime minister in the previous administration led by Thaksin's brother-in-law, Somchai Wongsawat.