"The time for diplomacy is now," she said at her confirmation hearing to replace Colin Powell as America's top diplomat.
Rice insisted that the administration's actions in the aftermath of Sept. 11, including wars in Afghanistan and Iraq, were "difficult, and necessary and right."
She promised to work to strengthen ties with old and new allies.
"If confirmed, I will work with members of Congress, from both sides of the aisle, to build a strong bipartisan consensus behind America's foreign policy."
There is no doubt that Rice will be confirmed and she's expected to be sworn in on Inauguration Day, reports CBS News White House Correspondent Bill Plante.
But she drew some sharp comments from Democrats on the Senate Foreign Relations Committee on the administration's sometimes go-it-alone approach to foreign policy.
"The time for diplomacy is long overdue," Sen. Joseph Biden of Delaware, the panel's senior Democrat, told her, saying the United States is "paying a heavy price" for the administration's policy in Iraq.
Rice told committee members the nation's "first challenge ... is to inspire the American people and the people of all free nations to unite in common cause to solve common problems"
She indicated that working to spread democracy through the Middle East — a top Bush administration priority — was a top challenge.
Rice said there remain "outposts of tyranny" in the world that require close attention, citing North Korea, Iraq, Cuba, Belarus, Zimbabwe and Myanmar, also known as Burma.
"We must remain united in insisting that Iran and North Korea abandon their nuclear weapons ambitions and choose instead the path of peace," she said.
Rice also cited her background, growing up in segregated Birmingham, Ala. "I am especially indebted to those who fought and sacrificed in the civil rights movement so that I could be here today," said Rice, who like Powell, is black.
She praised Powell, calling him "my friend and mentor."
If confirmed, Rice would be the first black woman, and only the second woman after Madeleine Albright, to be the nation's top diplomat.
Foreign Relations Committee Chairman Richard Lugar, R-Ind., opened Tuesday's hearing with warm words about Rice, who has served a mostly behind-the-scenes role at the White House for the past four years as Mr. Bush's national security adviser.
He said she was "highly qualified" to meet the foreign policy challenges the United States faces. "We are grateful that a leader of her stature is willing to step forward" and assume the secretary of state job, Lugar said.
"Our success in Iraq is critical," the senator told Rice, saying the Jan. 30 elections must go forward as scheduled.
Rice said that Mr. Bush's leadership after the Sept. 11 terror attacks has opened an opportunity "to help create a balance of power in the world that favors freedom."
She called the Sept. 11 attacks "a defining moment for our nation and the world."
"Under the vision and leadership of President Bush," Rice said, "our nation has risen to meet the challenges of our time: fighting tyranny and terror, and securing the blessings of freedom and prosperity for a new generation."
Rice said she recognized that "America's relations with the world's global powers will be critical."
"Our interaction with the rest of the world must be a conversation, not a monologue," she said.
Both Republican and Democratic senators said that they expected Rice to easily win enough votes for Senate confirmation. But they also said they expected tough questioning. The session offered a rare opportunity to ask the president's most trusted national security adviser about her views and her role in combating terrorism, planning for war in Iraq and the treatment of terrorism detainees.
Turning to the Middle East, Rice said "the stakes could not be higher."
"As long as the broader Middle East remains a region of tyranny and despair and anger, it will produce extremists and movements that threaten the safety of Americans and our friends," she said.
Rice brings a colorful biography to the job. She is a classically trained pianist who has performed with Yo-Yo Ma. She is a skilled figure skater who shares Mr. Bush's passion for exercise, and follows professional sports in obsessive detail. Mr. Bush joked in nominating her that her dream job is really to be commissioner of the National Football League.
Rice, who is single, was a college student at 15 and a university professor at 26. She was later provost of Stanford University, and has written several books.
Her previous Washington jobs, including a stint as a foreign policy adviser for Mr. Bush's father, President George H.W. Bush, did not require Senate confirmation and the intense scrutiny that goes with it.