The ruling by the California 2nd District Court of Appeal came less than three months after former cardiologist Conrad Murray was released after serving two years in jail for causing the King of Pop's death in June 2009.
The 68-page ruling includes lengthy recitations of the evidence against Murray, who was convicted in 2011 of giving Jackson, 50, a lethal dose of the anaesthetic propofol while the superstar was preparing for a series of comeback concerts at London's O2 arena called This Is It.
The six-week trial focused on Murray's care of Jackson, including nightly doses of propofol to help the entertainer sleep.
In its opinion, the Los Angeles appeal court determined that superior court judge Michael Pastor was within his right to impose the maximum sentence of four years.
Murray's "callous disregard for Mr Jackson's health and safety was shown throughout the trial from the manner in which he administered a number of dangerous drugs to Mr Jackson without the appropriate medical equipment, precautions or personnel in place, and to the manner in which he left Mr Jackson unattended", the opinion states.
"The evidence demonstrated that Mr Jackson was a vulnerable victim and that (Murray) was in a position of trust, and that (Murray) violated the trust relationship by breaching standards of professional conduct in numerous respects," it said.
The former doctor was released from jail in October due to a change in California law requiring non-violent offenders to serve their sentences in county jails and as a result of credits for good behaviour.
In his appeal, Murray argued that the judge who oversaw the case improperly excluded jurors from hearing key evidence and should have sequestered jurors.
But the appeal court disagreed and said it found no errors in the judge's rulings, including one allowing the trial to be televised.
Murray's trial lawyers attempted to introduce evidence of Jackson's financial difficulties and his treatment by other doctors, but Judge Pastor ruled evidence on those issues would be irrelevant.
Lawyer Valerie Wass, who represented Murray in the appeal, said she was disappointed but not surprised by the ruling.
She said she had not spoken to Murray since the opinion was issued but his intention has been to challenge his conviction to higher courts if necessary.