The former NBA player and coach will be introduced at a news conference on Friday afternoon.
"I'm excited to be the new head coach of the LA Sparks," Fisher said in the team's release. "There is no finer organization in the WNBA and I can't wait to work with our ownership group, front office, talented players, and staff to cement a culture of sustained excellence, which is what L.A. basketball fans demand - and deserve."
Fisher moves to the WNBA ranks having last coached the New York Knicks from 2014 to 2016. He moved directly into that job after his 18-year playing career ended, during which he won five NBA championships with the Los Angeles Lakers.
The Sparks are owned by a group which includes Lakers legend and current team president Magic Johnson.
Brian Agler, who coached the Sparks for the last four seasons, resigned last week.