Sinclair, 51, had been accused of twice forcing a female captain under his command to perform oral sex on him during a three-year extramarital affair. But the Army's case against Sinclair crumbled in recent weeks as questions arose about whether the woman had lied in a pre-trial hearing.
The defense provided a copy of the plea agreement approved and signed by a high-ranking general overseeing the case. Sinclair is expected to appear Monday morning in court at Fort Bragg.
The married 27-year Army veteran pleaded guilty earlier this month to having improper relationships with three subordinate officers, including the female captain who accused him of assault. He also pleaded guilty to adultery, which is a crime in the military.
Under the plea deal reached this weekend, Sinclair will also admit abusing a government credit card he used while traveling to visit his mistress.
Defense attorney Richard Scheff said that Sinclair is admitting to his mistakes, put pointed out that the general is pleading guilty to behavior that likely wouldn't be criminal in the civilian world.
"After wasting millions of taxpayer dollars, the Army finally admitted what it's known for many months: General Sinclair is innocent of sexual assault," Scheff said. "Brigadier General Sinclair has admitted to mistakes that are normally a matter between husbands and wives, or employees and HR departments. It's time to put this matter to rest."
A spokesman for Fort Bragg commander Maj. Gen. Clarence K.K. Chinn, who approved Sinclair's plea deal, could not immediately be reached for comment.
According to the defense, a separate agreement reached with Chinn will dictate what punishments Sinclair will receive. In theory, he faces more than 15 years in prison, though the plea agreement is unlikely to require anything close to the maximum penalties. Sinclair may also be forced to retire at reduced rank, costing him dearly in pension benefits.
That part of the agreement will remain secret until after the judge overseeing the case, Col. James Pohl, conducts a sentencing hearing later this week. That process will include testimony from about 20 witnesses. It was not immediately clear whether his primary accuser will be among those called to the stand. The Associated Press generally does not name those who say they were victims of sexual assault.