Speier took 75 percent of the vote, beating Republican businessman Greg Conlon's 19 percent in the heavily Democratic territory, complete unofficial election results showed.
Speier took office after a special election was held April 8 to determine who would fill the 12th Congressional District seat left vacant by the passing of U.S. Rep. Tom Lantos, who died Feb. 11 due to complications from esophageal cancer.
The congressman was diagnosed with esophageal cancer in late December 2007. Lantos announced that he would not seek reelection to the U.S. House of Representatives on Jan. 2, but had committed to serving the rest of his 14th term through December of this year, spokeswoman Lynne Weil said.
Lantos was the only Holocaust survivor to be elected to Congress and served as a senior member of the House Committee on Oversight and Government Reform. He was the founding co-chairman of the Congressional Human Rights Caucus, and was elected chairman of the House Committee on Foreign Affairs in January 2007, according to Weil.
The Congressman endorsed Speier before his death at 80 years old. Speier was sworn into office April 10 and currently sits on The House Committee on Financial Services and The Committee on Oversight and Government Reform, according to her Web site.
Before taking public office, Speier served as a legal advisor to Congressman Leo Ryan and in 1978 accompanied Ryan to Jonestown, Guyana to investigate the People's Temple, according to Speier's Web site. During the trip, Ryan was fatally shot and Speier was shot five times.
Prior to joining Congress, Speier served 18 years in the California State Assembly and Senate. She also served as a member and as chair of the San Mateo County Board of Supervisors, according to her Web site.
In June, Speier received 91.6 percent of the vote from Democrats in a landslide victory for the Democratic spot in Tuesday's election. Conlon received about 64 percent of the Republican vote in June.
Green party nominee Barry Hermanson and Libertarian nominee Kevin Dempsey Peterson both ran unopposed within their parties and were on the ballot. Peterson received about 2.1 percent of the vote and Hermanson received about 1.9 percent, according to complete unofficial election results. Peace and Freedom Party candidate Nathalie Hrizi received 1.9 percent of the vote.