Prosecutors say he acted with “gross negligence” and gave Jackson a lethal dose of the sedative propofol, on the night he died in June 2009.
The defence says Jackson gave himself too much of the drug, a sleeping aid.
If convicted, Dr Murray, 58, could face four years in jail and the loss of his medical licence.
In Tuesday’s opening statement, lead prosecutor David Walgren told the court the evidence would show “Conrad Murray repeatedly acted with gross negligence, repeatedly denied appropriate care to his patient, Michael Jackson”.
“That misplaced trust… cost Michael Jackson his life.”
The court heard a recording of Jackson slurring while talking about planned comeback concerts.
Mr Walgren said the audio, aired in public for the first time, had come from Dr Murray’s mobile phone.
“When people leave my show, I want them to say, ‘I’ve never seen nothing like this in my life’,” says the voice on the audio.
The prosecutor said Jackson’s difficulty in speaking on the recording showed that Dr Murray ought to have realised the star should not have taken any more propofol.
Mr Walgren said that after administering a dose of the drug on the date of Jackson’s death, Dr Murray had not been attentive to the star’s health.
The prosecutor said the doctor had left to go to the bathroom and checked his mobile phone.
“He [Murray] left him [Jackson] there, abandoned him to fend for himself,” the prosecutor said.
Mr Walgren said when Dr Murray found Jackson unconscious, he did not immediately call the emergency services, instead telling a bodyguard to do so 20 minutes later.
Dr Murray also did not mention to paramedics or emergency room doctors that he had administered propofol, according to the prosecutor.
Hundreds of Jackson fans gathered outside court as the trial began with opening statements from defence and prosecution. The proceedings are being televised and broadcast online.
Jackson choreographer Kenny Ortega was set to be the first prosecution witnesses to take the stand.
Mr Ortega was expected to lead the court through some footage from Jackson’s final rehearsals as the 50-year-old star prepared for his series of comeback concerts.
That video eventually became part of a documentary, This Is It, directed by Mr Ortega.
A judge has blocked some details of Jackson and Dr Murray’s lives being discussed at the trial.
Jackson’s history with drugs and financial troubles, as well as Dr Murray’s debts and personal affairs, will not come out in court.
Multiple witnesses, including security guards, paramedics and emergency room doctors are to be called.
The prosecution also plans to play a recording of Dr Murray’s police interview two days after Jackson’s death, in which the doctor says he gave the singer propofol for his insomnia.
The disclosure led to charges being brought against Dr Murray in February 2010.
Propofol is usually administered intravenously, often during surgery.
Medical experts are expected to testify about the sedative’s effects, as well as how a trace amount of the drug was found in Jackson’s stomach.
Defence lawyers are putting forward the theory that Jackson drank or somehow administered an extra dose of propofol after Dr Murray left.
The trial is expected to last about five weeks.
The jury comprises seven men and five women, one African American, six whites and five Latinos.