Hill garnered 73 percent of the vote, shutting out Republican opponent Catherine Brinkman in the heavily Democratic district.
Brinkman, former chair of the California Young Republicans, received 23 percent of the vote and Libertarian Brian Perry received support from 4 percent of voters, according to complete unofficial election results.
Hill, a San Francisco native who has lived in San Mateo County since 1969, has moved fluidly through the county's elected positions before considering state politics two years ago.
The supervisor said today he never intended to go into politics when, as a businessman and president of his neighborhood homeowners' association in San Mateo, he became frustrated with city government.
"I was upset with the direction the city of San Mateo was moving in," Hill said. "I decided to run for City Council to change that direction."
Hill was elected to the City Council in 1991 and served two terms before an opening on the San Mateo County Board of Supervisors presented itself. Hill was elected to District 2, which includes Belmont, Foster City and San Mateo, in 1998, then again in 2002 and 2006.
His interest in state politics began about two years ago, when another opportunity arose.
"There were opportunities here, and I could see the opportunity to really participate in solving the state's challenges and problems and bringing the state back to the quality I remember when I was growing up," Hill said.
Incumbent Assemblyman Gene Mullin, D-South San Francisco, will term out of office in 2009 and endorsed Hill to fill his seat. U.S. Rep. Jackie Speier, D-San Francisco/San Mateo, also endorsed the supervisor.
Hill, who earned a Bachelors of Arts degree in history from the University of California, Berkeley and a permanent teaching credential in secondary education from San Francisco State University, will begin training for his new position Friday and continue with training next week.
He said he will issue his letter of resignation to the Board of Supervisors for his resignation to be effective Nov. 30. The Board will then have the option of appointing a new member or holding a special election, estimated to cost about $1.7 million.
"To me that's the real incentive for the Board to make an appointment," said Hill, who has two years left in his current supervisor term before he would have termed out of office.
If the Board were unable to make a decision, the county's election office would call for a special election.
After being sworn into the State Assembly Dec. 1, Hill said he hopes to hit the ground running.
"One of the things I think is important is that we need to get our arms around the state budget process with some strategic reforms," Hill said. "It's crucial or every year's (budget) will be like this year's (budget)."
The newly elected legislator also said he will work toward bipartisan efforts with Republican members of the state legislature.
"It's not working the way it is today," he said.
Health care reform will also be a top priority during his two-year term, Hill said.
The supervisor's Election Day celebration included celebration of President Elect Barack Obama and a look toward the future.
"I think that, more importantly, this election was all about change, and I'm excited to be part of that," Hill said.