The jury deliberated three days, with their decision coming moments after Judge Thayer Fremont-Smith reduced from 13 to 12 the number of jurors who had to agree on a verdict.
Mudge, a cardiologist, and Lewis' widow, Donna Harris-Lewis, were not in the courtroom when the verdict was read.
An earlier trial exonerated two doctors who consulted with Mudge, but the jury deadlocked while trying to reach a conclusion as to Mudge's liability in Lewis' 1993 death.
Mudge and his wife thanked the jury and the judge.
"We are gratified by their obvious attention to the evidence in deciding this most complex case," the Mudges said in a statement read by his lawyer, William Dailey.
Jurors were asked to decide whether Mudge provided Lewis with substandard care, and whether that negligence caused the player's death.
The judge, who presided over both trials, said there was no question in either trial that Mudge was an eminent physician and that Harris-Lewis was a loving and dedicated wife and mother.
"I hope the time has now come when everybody involved in the case can count their many blessings and move on with their lives," he said.
In the first trial, Mudge argued his ability to diagnose Lewis' condition was hindered because the player concealed a history of cocaine use. But the judge instructed this jury it should not consider whether drug use hastened Lewis' death.
Mudge and Harris-Lewis agreed to reduce to 12 the number of jurors needed for a verdict in hopes of another hung jury.
"I think everybody wanted to have this case resolved," said lawyer Neil Rossman, who called Harris-Lewis with the jury's decision. "We took our chances."
It was not immediately known if Harris-Lewis would appeal.
Lewis collapsed during an NBA playoff game, and a "dream team" of a dozen doctors diagnosed the problem as a potentially fatal heart arrhythmia. Unhappy with the diagnosis, Lewis and his wife walked out of the hospital and eventually went to Mudge.
Mudge said Lewis had a benign fainting disorder and would eventually be able to play basketball "without limitation." But on July 27, Lewis collapsed at the Celtics' practice facility and died.
"He (Mudge) didn't do anything," Rossman, the lawyer for Lewis' widow and children, Reggie Jr. and Reggieana, said during the second trial. "Every one of those days that Lewis was out there he was a dead man walking. It was just a matter of time."
Mudge contended even though he said publicly Lewis could eventually resume his NBA career, he had not ruled out a heart problem. He also cautioned Lewis to take his medication and not exert himself -- instructions his patient ignored, Mudge said.
Harris-Lewis could not immediately be reached for comment, but her lawyer said she needed some time to accept the news.
"She needs to compose herself and deal with what has happened here," Rossman said. "She'll never get over the loss of her husband, and the children will never get over the loss of their father. But she's had the opportunity to have this question answered by a jury of her peers."
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