Democrat John Perez of Los Angeles said creating jobs as the state struggles with an unemployment rate above 12 percent will be his legislative priority.
He also wants to start healing rifts between Democrats and Republicans that have made it difficult for either house to pass meaningful legislation in recent years.
Perez announced during his acceptance speech that he will appoint two Republicans to serve as chairs of Assembly committees. While Republicans are the minority in the Assembly and Senate, he said their ideas deserve to be considered.
Getting both sides to work together, he said, will be key to solving the state's ongoing fiscal crisis.
California faces a budget deficit of about $20 billion through June 2011. Democrats have argued against deep spending cuts, while Republicans oppose tax increases.
"We don't have sufficient resources to meet all our needs, but that cannot be an excuse to turn on each other," Perez told his colleagues in a packed Assembly chamber.
The speaker position is being vacated by Assemblywoman Karen Bass, another Los Angeles Democrat, who is running for Congress and will be termed out at the end of the year.
Perez, who becomes the 68th Assembly speaker, can serve four more years in the Assembly.