The school handed a termination letter to Leach's attorney, Ted Liggett, just minutes before the two sides were to appear in a Lubbock, Texas, courtroom for a hearing on the coach's suspension.
Liggett said Texas Tech general counsel Pat Campbell approached him outside the courtroom and told him that win, lose or draw in the hearing, Leach was out effective immediately.
When Liggett entered the courtroom he told the judge there was no need for the hearing on Leach's request that he be reinstated to coach the Alamo Bowl.
As for Leach's reaction, Liggett said, "Well, he's not thrilled."
Liggett said he planned to file a lawsuit on Leach's behalf against the school "soon."
"We can guarantee that the fight has just begun," he said.
Liggett said Leach's side has evidence that shows the decision to suspend the coach was without merit.
"So they pulled the trigger," Liggett said. "They don't want that coming out."
In February, Leach and the school agreed to a five-year, $12.7 million contract. According to terms of the deal, Leach was due a $800,000 bonus on Dec. 31 if he were still the head coach at Texas Tech.
Leach was suspended by the university on Monday after receiver Adam James alleged the coach twice confined him to small, dark spaces while the team practiced.
James is the son of former NFL player and ESPN analyst Craig James.
"We appreciate that the university conducted a fair and thorough investigation," said a statement from the James family. "From the family's point of view this has always been about the safety and well being of our son and of all the players on the team."
Texas Tech plays Michigan State on Saturday in the Alamo Bowl in San Antonio.
Tech is the second Big 12 school to launch an internal investigation into a coach's treatment of his players.
On Nov. 16, Kansas investigated Mark Mangino, who got a big raise after he was national coach of the year and went 12-1 in 2007. Some players said he was insensitive, though others defended him.
Mangino resigned Dec. 3 after reaching a settlement with the school that was later disclosed as a $3 million buyout.
In an affidavit included in Tuesday's court filing, Leach said he "would never intentionally harm or endanger a player" and that he has been "forced into this situation without being afforded any process." He also said "absolutely" no evidence had been given to him that showed he had violated any university rules or standards.
Several former and current Texas Tech players and coaches defended Leach and harshly criticized James' work ethic in e-mails obtained by CBSSports.com.
Among those were former Texas Tech wide receiver Eric Morris, who wrote that James was "never known as a hard worker" and "seemed to have a negative attitude toward the football program the majority of the time."
Morris told The Associated Press on Wednesday the letters were written as school administrators began looking into the incident, before Leach was suspended. Morris said they wanted to show their support for Leach and show James' possible motives.
Morris said he spoke with Leach as the incident began unfolding.
"He told me he would never do anything" to harm a player, Morris said. "He was trying to hold someone accountable."
Leach's dismissal comes a year after he was Big 12 coach of the year and led Tech to the best season in the history of the program. The Red Raiders went 11-2 last season.
A quirky coach sometimes called a mad scientist because of pass-happy offense, Leach arrived in West Texas in 2000 with his high-octane spread offense. Since then, eight time has a Texas Tech quarterback led the nation in passing.
He parlayed his penchant for pirate lore into his coaching, telling his players they need to "swing their swords" to perform at their best. He began to not acknowledge players' injuries in 2003 to the media.
In 10 seasons, he won 84 game, surpassing predecessor Spike Dykes this season as the winningest coach at the school.
He was not able to out-recruit Big 12 South rivals Texas and Oklahoma, but during his tenure the Red Raiders challenged those teams better than they ever had before.
The year before he came to Lubbock, Leach was offensive coordinator under Bob Stoops at Oklahoma. Before that he spent two years at Kentucky and five years at Valdosta State in Georgia.
Quite an ascension from the being the head coach for a European League team in Finland.
While piling up victories, he's also occasionally spoken to Donald Trump — an acquaintance since the time Leach tried to just drop in on Trump before even meeting him while visiting New York.
Not unlike Bob Knight when he came to coach the Red Raiders basketball team for 6 1/2, Leach has raised the profile of the city and the school. He appeared on "60 Minutes" and been profiled in the New York Times Magazine.
For his success on the field and unique personality off it, he has become generally adored by Texas Tech fans.
He's handed out dating advice on his weekly local show, done the weather forecast for a Lubbock TV station and drawn cheers by buying barbecue for the thousands of students camped out at the stadium before a big game.
Leach's name surfaced in recent years when other coaching spots have opened up. Two years ago it was Arkansas and UCLA. Last year there were reports Tennessee might be interested and he traveled to Washington during contentious contract extension negotiations when the school was looking for a new coach.