Ashlee Buzzard — accused of killing her 9-year-old daughter Melodee Buzzard — has pleaded not guilty to the crime.

The 40-year-old entered her plea in a Santa Barbara, California courtroom Friday … and prosecutors confirmed they’d pursue a life sentence against Buzzard, but not the death penalty.

As you know … Ashlee was arrested for Melodee’s murder Tuesday after her daughter initially went missing in October.

Melodee and Ashlee were seen on security footage wearing wigs at a Santa Barbara car rental on October 7.

Melodee was last seen on camera with her mother near the Colorado-Utah border on October 9 … where the Chevrolet Malibu Ashlee rented was seen driving with New York plates. The original plates were restored when the car was returned the following day … but Melodee was not with her mother.

Family members have spoken to the media in the aftermath of the arrest … claiming she’s “extremely mentally unstable.”