Officers Joe Cirrito and Kristina Tudor left the L.A. Police Academy for Sacramento.
The 12-day run will take them to the California Peace Officer's Memorial.
Along the way, they're raising money for the Los Angeles Police Memorial Foundation and the group, Concerns of Police Survivors, also knowns as C.O.P.S.
"It's probably going to be a very vulnerable time but also a time to remember. It's going to be an epic journey," Tudor said.
The two officers are completing the run during their off-duty days, and they'll be assisted by a team of some 40 volunteers along the way.