Fisher made the announcement in a brief statement released by FSU on Monday night.
A source told ESPN.com on Tuesday that FSU officials hadn't seen video of Johnson punching the woman until it was published on the Tallahassee Democrat website Monday. The source said Fisher didn't see the video until Monday night -- shortly before he dismissed Johnson from the team -- because he was vacationing in a remote area of West Virginia.
Johnson, who was named Florida's "Mr. Football" as a senior at First Coast High School in Jacksonville, Florida, was indefinitely suspended from the team in June. He was charged with misdemeanor battery for striking the 21-year-old woman during an argument June 24. He surrendered to Tallahassee police on June 30 and was released on $500 bond.
Florida State president John Thrasher, in a statement released Tuesday, said he fully supported the actions Fisher took to suspend and then dismiss Johnson from the program.
"While it is always important to adhere to due process, having now seen the physical altercation captured on video, there is no question in my mind that Coach Fisher made the correct decisions," Thrasher said. "I expect all students at Florida State University, including student-athletes, to adhere to the highest level of conduct. I have no tolerance for the kind of behavior exhibited in this case. Florida State University was forged from an outstanding college for women and has a long tradition of being a caring community that demands students be treated with dignity and respect."
The video, which was captured by security cameras in a bar near the FSU campus, shows Johnson trying to push past the woman, who was waiting to order at the bar. The woman turned toward Johnson, who grabbed her right arm after she raised it in a fist. The woman raised her knee and swung at Johnson with her left arm, and then he punched her in the face.
According to the Tallahassee Police Department incident report, the woman, an FSU student, suffered bruising near her left eye, swelling of the left cheek and upper lip, and a small cut near the bridge of her nose.
State's attorney Willie Meggs, who decided to charge Johnson after seeing video of the incident, said the woman still had a black eye when he met with her last week.
Johnson's family has retained prominent criminal defense and trial attorney Jose Baez, who is best known for obtaining an acquittal in the Casey Anthony murder trial in Orlando, Florida.
The state's attorney's office said Baez entered a written not guilty plea on his client's behalf on July 2. Johnson's first court appearance is scheduled in Leon County Court on July 22.
"While it is clear from the video that De'Andre Johnson was not the initial aggressor, his family wants to take the lead in helping him learn and grow from this experience," Baez said Monday in a statement. "He is currently participating in community service and faith-based programs focused on battered women, substance abuse and the empowerment of children.
"De'Andre is extremely embarrassed by this situation and would like to express his heartfelt apologies to everyone, including those who were directly affected, Coach Fisher and his teammates, the entire Florida State University community, as well as his family and friends."
Johnson, who enrolled at FSU in January after graduating early from high school, wasn't thought to be a contender for the Seminoles' starting job this coming season. Junior Sean Maguire and Notre Dame transfer Everett Golson, who enrolled at FSU this summer, are believed to be the top choices to replace 2013 Heisman Trophy winnerJameis Winston, who was the No. 1 pick by the Tampa Bay Buccaneers in April's NFL draft.
Freshman Deondre Francois of IMG Academy in Bradenton, Florida, also joined FSU's quarterback competition this summer. He was ranked the country's No. 3 dual-threat quarterback and No. 42 overall prospect in the ESPN 300.
Johnson was ranked the No. 7 dual-threat quarterback as a senior. He passed for 3,710 yards and 47 touchdowns while running for 398 yards and nine scores the past season as he led First Coast High to a 12-1 record. He finished his prep career with 11,697 total yards.
ESPN.com Florida State reporter Jared Shanker contributed to this report.
FSU releases QB Johnson in wake of bar incident
ESPN college football reporter Mark Schlabach discusses Florida State releasing freshman quarterback De'Andre Johnson after video was released of him punching a woman at a bar.