Spagnoli will take over the post on Jan. 10.
"Chief Spagnoli is an exceptional police leader who has a history of positive innovations and partnerships," San Leandro City Manager Steve Hollister said in a statement.
Spagnoli has spent four years as Benicia's police chief. Prior to that, she spent 16 years serving the San Carlos Police Department, eight as a commander.
She holds a bachelor's degree in human services management and a master's degree in human resource management, both from College of Notre Dame in Belmont.
"I am extremely honored to be selected as San Leandro's next police chief," said Spagnoli in a statement.
"I am committed to building on the existing traditions of excellence and working on partnership with the community to continue to enhance levels of service, safety and security," she said.