The deputy claimed that he was shot in the shoulder Wednesday, which triggered a massive manhunt and evacuations of an apartment complex next to the agency's Lancaster station, authorities said.
Deputy Angel Reinosa, 21, had two holes in his shirt the day he claimed to be shot by a sniper.
He was heard calling in the shooting over emergency radios.
LANCASTER SHOOTING: Wounded deputy calls in own shooting in dramatic audio
"I have taken shots from the north of the Lancaster helipad," the deputy is heard saying over the radio. "I think I'm hit in the right shoulder."
When investigators met with Reinosa on Saturday for follow-up interviews about the incident, they saw no visible injuries on his shoulder. Officials said Reinosa confessed to cutting the holes in his shirt with a knife and that he was never shot.
"There was no sniper, no shots fired and no gunshot injury sustained to his shoulder. Completely fabricated," said Capt. Kent Wegener with the Los Angeles County Sheriff's Department.
Reinosa was expected to be relieved of his duty and will face criminal charges for filling a false report of an emergency, officials said.
A motive had not been determined in the ongoing investigation.
"Most of his statement was self-serving, didn't make a whole lot of sense, but he didn't get into detail as to why he cut the holes or why he fabricated this story. No motivation," Wegener said.
The Los Angeles County District Attorney's office will now determine whether Reinosa will face additional charges.