"I, the engineer Abdo Hussameddin, the deputy oil minister ... announce my defection from the regime and my resignation," he said in a four-minute video posted on social networking site YouTube.
He added that he was "joining the revolution of the people who reject injustice and the brutal campaign of the regime, which is seeking to crush the people's demand for freedom and dignity."
The 57-year-old engineer who is married and has four children, denounced Russia and China for backing President Bashar al-Assad, saying they were not "friends of the Syrian people but partners in the killing of the Syrian people."
He said he had worked for the Syrian government for 33 years and did not wish to end his life "serving a criminal regime".
"That is why I have joined the right path knowing that this regime will burn down my house, hunt down my family and fabricate lies," said Hussameddin, who was appointed deputy oil minister in August 2009. He advised his colleagues to abandon "this sinking ship" and said he was also resigning from the ruling Baath party.
Rami, an activist who shot the video of Hussameddin and posted it on YouTube, told AFP in Beirut that the opposition had helped arrange the defection. He said the video was shot on Wednesday and that Hussameddin had now gone underground. He asked that the location of where the video was shot not be disclosed for safety reasons.