Sheriff spokesman John Urquhart said Paul Schene was fired for a number of policy violations, including the incident captured on video.
Urquhart said Schene pleaded his case before Sheriff Sue Rahr on September 9, but she found the violations to be supported and agreed with the recommendation that Schene be fired.
The department violations included making false statements, conduct that is criminal in nature, excessive or unnecessary force and discrimination in civility or bigotry, among others, Urquhart said.
The security video shows Schene shoving and kicking a 15-year-old girl in a holding cell after her arrest.
Schene was charged with fourth-degree assault in connection with the Nov. 29 incident in a holding cell at SeaTac City Hall. Schene pleaded not guilty to the charge.
According to court records, Schene and another deputy arrested a pair of 15-year-old girls for investigation of auto theft after they were stopped driving a stolen car.
The girls were taken to the holding facility at SeaTac City Hall for fingerprinting and other processing.
Trouble allegedly began after Schene escorted one of the teens into a holding cell. While trying to take her shoes off, the girl kicked off her left shoe, which struck the deputy in the shin, the document said.
The video shows the girl crossing her arms and kicking off her shoe through the doorway of the cell. The video then shows the deputy's violent response.
Court records say Schene kicked the teen in the upper thigh area, then pushed her into the back wall before taking her down on the floor and putting her in a handcuffing position. Once on the floor, Schene grabbed the teen's hair and yanked her head and neck upward, the document said.
With the help of the other deputy, Schene then handcuffed the teen, the document said. While doing so, Schene appeared to strike the teen twice overhead, investigators noted.
The second deputy was a trainee at the time and is not under investigation, officials said.
The teen seen in the video, Malika Calhoun, told the CBS "The Early Show" in March that the attack was "horrible."
"I was yelling. I was like, `This isn't - I'm not resisting, I'm not resisting,' and he said, `Whether you're resisting or not, that was assault,"' Calhoun said. "Then he just kept doing it and kept going and going."
Schene told investigators through an e-mail conversation with his lawyer that once the girl kicked her shoe at him, he entered the cell to "prevent another assault," according to court documents. Schene also said the girl refused to comply with instructions in the holding area.
Schene was investigated previously for shooting two people - killing one - in the line of duty in 2002 and 2006. Both times his actions were found to be justified.
Schene is scheduled to go to trial for the assault charge in October.
Urquhart said the state will also review whether Schene should be barred from working as a law enforcement officer elsewhere in the state.