The decision came as members pushed toward a broader resolution to return U.N. weapons inspectors to Iraq after a yearlong absence.
All 15 members of the council voted in favor of the 180-day extension to the U.N. oil-for-food program, which allows Iraq to sell $5.2 billion in oil over six months to buy humanitarian goods for its people.
Friday's vote came in sharp contrast to one last week, when the United States only narrowly managed to get a weeklong extension.
Baghdad halted oil exports on Nov. 22 after the council approved a two-week extension to the program, but has since said it would resume pumping if the council passed the six-month continuation. Oil industry experts say exports could resume by Dec. 15 or 16.
Ahead of Friday's vote, Britain on Thursday formally introduced a comprehensive resolution that would not only improve the oil-for-food program but return weapons inspectors to Iraq. The resolution would suspend sanctions if Baghdad cooperates fully with inspectors and shows progress toward answering questions about its programs to build weapons of mass destruction.
Arms experts left Iraq in December 1998 ahead of airstrikes launched by the United States and Britain for what the two countries said was Iraq's failure to cooperate with weapons inspectors.
Iraq has barred the inspectors from returning until the Security Council lifts the economic sanctions it imposed after Baghdad's 1990 invasion of Kuwait.
British Ambassador Jeremy Greenstock, the current council president, wouldn't say whether he would schedule a vote on the comprehensive draft Saturday, as the United States wants, or give Russia and China more time.
"The point is that we are now on the run to a final vote," Greenstock said Thursday night.
Russia and China want more time and negotiations to alter elements of the draft resolution and neither has indicated how it would vote if the United States and Britain were to push for a vote Saturday.